[receover/mongodb] Graduate removeDatabaseAttr feature gate to stable (…

…#33642)

It's been 8 versions since the feature gate moved to beta. Seems like a
good to to graduate it to beta and remove the duplicated code

Fixes
#24972

.chloggen/stable-receiver-mongodb-removeDatabaseAttr.yaml

@@ -0,0 +1,22 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: receiver/mongodb
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Graduate receiver.mongodb.removeDatabaseAttr feature gate to stable"
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [24972]
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/mongodbreceiver/README.md

@@ -75,8 +75,7 @@ Details about the metrics produced by this receiver can be found in [metadata.ya
 
 See the [Collector feature gates](https://github.com/open-telemetry/opentelemetry-collector/blob/main/featuregate/README.md#collector-feature-gates) for an overview of feature gates in the collector.
 
-**BETA**: `receiver.mongodb.removeDatabaseAttr`
+**STABLE**: `receiver.mongodb.removeDatabaseAttr`
 
-The feature gate `receiver.mongodb.removeDatabaseAttr` is enabled by default but may be disabled.
-Unless disabled, it will remove the database name attribute from data points because it is already found on the resource.
-This feature gate will eventually be removed.
+The feature gate `receiver.mongodb.removeDatabaseAttr`  will remove the database name attribute from data points 
+because it is already found on the resource. This feature gate cannot be changed and will be removed soon.