Explicitly specify protobuf 27.2, repin maven deps

Resolves these warnings:

```txt
DEBUG: .../external/rules_jvm_external~/private/extensions/maven.bzl:154:14:
  The maven repository 'maven' is used in two different bazel modules,
  originally in 'com_engflow_bazel_invocation_analyzer'
  and now in 'protobuf'

DEBUG: .../external/rules_jvm_external~/private/extensions/maven.bzl:154:14:
  The maven repository 'maven' is used in two different bazel modules,
  originally in 'com_engflow_bazel_invocation_analyzer'
  and now in 'protobuf'

DEBUG: .../external/rules_jvm_external~/coursier.bzl:593:18:
    Found duplicate artifact versions
    com.google.code.gson:gson has multiple versions 2.11.0, 2.8.9
    com.google.guava:guava has multiple versions 33.2.1-jre, 31.1-jre
    com.google.truth:truth has multiple versions 1.4.3, 1.1.2
    org.mockito:mockito-core has multiple versions 5.12.0, 4.3.1
Please remove duplicate artifacts from the artifact list so you do not
get unexpected artifact versions
```

See also:

- Duplicate maven repositories when importing bazel_deps that use
  maven.install
  bazel-contrib/rules_jvm_external#916

- Using maven as the repo name causes duplicate warnings when using
  bzlmod
  protocolbuffers/protobuf#16839

- MODULE.bazel doesn't define @maven repository
  protocolbuffers/protobuf#17176

- Stop including extra artifacts on maven.install()
  bazel-contrib/rules_jvm_external#1168

- Use a custom name for the maven repository (maven_protobuf)
  protocolbuffers/protobuf#17190

MODULE.bazel

@@ -13,6 +13,7 @@ bazel_dep(name = "buildifier_prebuilt", version = "6.4.0")
 bazel_dep(name = "platforms", version = "0.0.10")
 bazel_dep(name = "rules_jvm_external", version = "5.3")
 bazel_dep(name = "rules_proto", version = "6.0.2")
+bazel_dep(name = "protobuf", version = "27.2")
 
 # =========================================
 # Java dependencies

maven_install.json

@@ -1,15 +1,7 @@
 {
   "__AUTOGENERATED_FILE_DO_NOT_MODIFY_THIS_FILE_MANUALLY": "THERE_IS_NO_DATA_ONLY_ZUUL",
-  "__INPUT_ARTIFACTS_HASH": 342765507,
-  "__RESOLVED_ARTIFACTS_HASH": 1160254299,
-  "conflict_resolution": {
-    "com.google.code.gson:gson:2.8.9": "com.google.code.gson:gson:2.11.0",
-    "com.google.errorprone:error_prone_annotations:2.3.2": "com.google.errorprone:error_prone_annotations:2.28.0",
-    "com.google.guava:guava:31.1-jre": "com.google.guava:guava:33.2.1-jre",
-    "com.google.j2objc:j2objc-annotations:1.3": "com.google.j2objc:j2objc-annotations:3.0.0",
-    "com.google.truth:truth:1.1.2": "com.google.truth:truth:1.4.3",
-    "org.mockito:mockito-core:4.3.1": "org.mockito:mockito-core:5.12.0"
-  },
+  "__INPUT_ARTIFACTS_HASH": -1317769858,
+  "__RESOLVED_ARTIFACTS_HASH": 2075160190,
   "artifacts": {
     "com.google.auto.value:auto-value-annotations": {
       "shasums": {
@@ -60,13 +52,6 @@
       },
       "version": "33.2.1-jre"
     },
-    "com.google.guava:guava-testlib": {
-      "shasums": {
-        "jar": "aadc71b10d5c3ac474dd16be84cfb18d257e584d1e0a59f8cab64ef4376226ce",
-        "sources": "7149659f8966197dcd91a42183349f862d3973f8e65efe6d03e678464fa13bfd"
-      },
-      "version": "31.1-jre"
-    },
     "com.google.guava:listenablefuture": {
       "shasums": {
         "jar": "b372a037d4230aa57fbeffdef30fd6123f9c0c2db85d0aced00c91b974f33f99",
@@ -181,14 +166,6 @@
       "com.google.j2objc:j2objc-annotations",
       "org.checkerframework:checker-qual"
     ],
-    "com.google.guava:guava-testlib": [
-      "com.google.code.findbugs:jsr305",
-      "com.google.errorprone:error_prone_annotations",
-      "com.google.guava:guava",
-      "com.google.j2objc:j2objc-annotations",
-      "junit:junit",
-      "org.checkerframework:checker-qual"
-    ],
     "com.google.truth.extensions:truth-java8-extension": [
       "com.google.truth:truth",
       "org.jspecify:jspecify"
@@ -271,15 +248,6 @@
       "com.google.common.xml",
       "com.google.thirdparty.publicsuffix"
     ],
-    "com.google.guava:guava-testlib": [
-      "com.google.common.collect.testing",
-      "com.google.common.collect.testing.features",
-      "com.google.common.collect.testing.google",
-      "com.google.common.collect.testing.testers",
-      "com.google.common.escape.testing",
-      "com.google.common.testing",
-      "com.google.common.util.concurrent.testing"
-    ],
     "com.google.j2objc:j2objc-annotations": [
       "com.google.j2objc.annotations"
     ],
@@ -508,8 +476,6 @@
       "com.google.guava:failureaccess",
       "com.google.guava:failureaccess:jar:sources",
       "com.google.guava:guava",
-      "com.google.guava:guava-testlib",
-      "com.google.guava:guava-testlib:jar:sources",
       "com.google.guava:guava:jar:sources",
       "com.google.guava:listenablefuture",
       "com.google.j2objc:j2objc-annotations",