deps: update grpc dependencies to v1.68.2 (#3420)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [io.grpc:grpc-core](https://redirect.github.com/grpc/grpc-java) |
`1.68.1` -> `1.68.2` |
[![age](https://developer.mend.io/api/mc/badges/age/maven/io.grpc:grpc-core/1.68.2?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/maven/io.grpc:grpc-core/1.68.2?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/maven/io.grpc:grpc-core/1.68.1/1.68.2?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/io.grpc:grpc-core/1.68.1/1.68.2?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
| [io.grpc:grpc-bom](https://redirect.github.com/grpc/grpc-java) |
`1.68.1` -> `1.68.2` |
[![age](https://developer.mend.io/api/mc/badges/age/maven/io.grpc:grpc-bom/1.68.2?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/maven/io.grpc:grpc-bom/1.68.2?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/maven/io.grpc:grpc-bom/1.68.1/1.68.2?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/io.grpc:grpc-bom/1.68.1/1.68.2?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

> [!WARNING]
> Some dependencies could not be looked up. Check the Dependency
Dashboard for more information.

---

### Release Notes

<details>
<summary>grpc/grpc-java (io.grpc:grpc-core)</summary>

###
[`v1.68.2`](https://redirect.github.com/grpc/grpc-java/releases/tag/v1.68.2)

[Compare
Source](https://redirect.github.com/grpc/grpc-java/compare/v1.68.1...v1.68.2)

##### Bug Fixes

- api: When forwarding from Listener onAddresses to Listener2 continue
to use onResult
([https://github.com/grpc/grpc-java/pull/11688](https://redirect.github.com/grpc/grpc-java/pull/11688)).
This fixes a 1.68.1 "IllegalStateException: Not called from the
SynchronizationContext" regression
([#&#8203;11662](https://redirect.github.com/grpc/grpc-java/issues/11662))
that could be seen in certain custom NameResolvers
- okhttp: If the frame handler thread is null do not schedule it on the
executor
([https://github.com/grpc/grpc-java/pull/11716](https://redirect.github.com/grpc/grpc-java/pull/11716)).
This fixes a 1.68.1 NullPointerException regression when a custom
transportExecutor was provided to the channel and it did not have enough
threads to run new tasks

##### Improvements

- examples: Use xds-enabled server and xds credentials in
example-gcp-csm-observability
([https://github.com/grpc/grpc-java/pull/11707](https://redirect.github.com/grpc/grpc-java/pull/11707))

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you
are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about these
updates again.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR was generated by [Mend Renovate](https://mend.io/renovate/).
View the [repository job
log](https://developer.mend.io/github/googleapis/sdk-platform-java).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzOS40Mi40IiwidXBkYXRlZEluVmVyIjoiMzkuNDIuNCIsInRhcmdldEJyYW5jaCI6Im1haW4iLCJsYWJlbHMiOltdfQ==-->

.cloudbuild/library_generation/library_generation.Dockerfile

@@ -51,7 +51,7 @@ FROM docker.io/library/python:3.12.7-alpine3.20@sha256:5049c050bdc68575a10bcb188
 
 ARG OWLBOT_CLI_COMMITTISH=6662ddc9cff57289c3c1d59224904d78087734b5
 ARG PROTOC_VERSION=25.5
-ARG GRPC_VERSION=1.68.1
+ARG GRPC_VERSION=1.68.2
 ARG JAVA_FORMAT_VERSION=1.7
 ENV HOME=/home
 ENV OS_ARCHITECTURE="linux-x86_64"

gapic-generator-java-pom-parent/pom.xml

@@ -26,7 +26,7 @@
     <!-- External dependencies, especially gRPC and Protobuf version, should be
         consistent across modules in this repository -->
     <javax.annotation-api.version>1.3.2</javax.annotation-api.version>
-    <grpc.version>1.68.1</grpc.version>
+    <grpc.version>1.68.2</grpc.version>
     <google.auth.version>1.30.0</google.auth.version>
     <google.http-client.version>1.45.0</google.http-client.version>
     <gson.version>2.11.0</gson.version>

gax-java/dependencies.properties

@@ -28,7 +28,7 @@ version.gax_httpjson=2.58.1-SNAPSHOT
 
 version.com_google_protobuf=3.25.5
 version.google_java_format=1.15.0
-version.io_grpc=1.68.1
+version.io_grpc=1.68.2
 
 # Maven artifacts.
 # Note, the actual name of each property matters (bazel build scripts depend on it).