[extension/filestorage] move feature gate to stable (#32374)

**Description:**

Moves the feature gate `extension.filestorage.replaceUnsafeCharacters`
to Stable stage, which means it cannot be disabled. This is according to
the schedule for this feature gate described in the File Storage
extension's
[README](https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/v0.97.0/extension/storage/filestorage/README.md#extensionfilestoragereplaceunsafecharacters).

**Link to tracking Issue:**

-
#3148

**Testing:**

No changes.

**Documentation:**

Updated version in which feature gate was moved to Beta.

.chloggen/filestorage-feature-gate-stable.yaml

@@ -0,0 +1,28 @@
+# 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: extension/filestorage
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Replace path-unsafe characters in component names
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [3148]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  The feature gate `extension.filestorage.replaceUnsafeCharacters` is now stable and cannot be disabled.
+  See the File Storage extension's README for details.
+# 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: []

extension/storage/filestorage/README.md

@@ -129,7 +129,7 @@ The schedule for this feature gate is:
 
 - Introduced in v0.87.0 (October 2023) as `alpha` - disabled by default.
 - Moved to `beta` in v0.92.0 (January 2024) - enabled by default.
-- Moved to `stable` in April 2024 - cannot be disabled.
-- Removed three releases after `stable`.
+- Moved to `stable` in v0.99.0 (April 2024) - cannot be disabled.
+- Removed in v0.102.0 (three releases after `stable`).
 
 [unicode_chars]: https://en.wikipedia.org/wiki/List_of_Unicode_characters

extension/storage/filestorage/extension.go

@@ -18,10 +18,11 @@ import (
 
 var replaceUnsafeCharactersFeatureGate = featuregate.GlobalRegistry().MustRegister(
 	"extension.filestorage.replaceUnsafeCharacters",
-	featuregate.StageBeta,
+	featuregate.StageStable,
 	featuregate.WithRegisterDescription("When enabled, characters that are not safe in file paths are replaced in component name using the extension. For example, the data for component `filelog/logs/json` will be stored in file `receiver_filelog_logs~007Ejson` and not in `receiver_filelog_logs/json`."),
 	featuregate.WithRegisterReferenceURL("https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/3148"),
 	featuregate.WithRegisterFromVersion("v0.87.0"),
+	featuregate.WithRegisterToVersion("v0.102.0"),
 )
 
 type localFileStorage struct {