[otel-data] Bump plugin version to release _metric_names_hash changes (elastic#126850)

Bump otel-data plugin version as elastic#120952 missed the bump.

(cherry picked from commit 5860ccb)

# Conflicts:
#	x-pack/plugin/otel-data/src/main/resources/resources.yaml

Author: carsonip

docs/changelog/126850.yaml

@@ -0,0 +1,5 @@
+pr: 126850
+summary: "[otel-data] Bump plugin version to release _metric_names_hash changes"
+area: Data streams
+type: bug
+issues: []

x-pack/plugin/otel-data/src/main/resources/resources.yaml

@@ -1,7 +1,7 @@
 # "version" holds the version of the templates and ingest pipelines installed
 # by xpack-plugin otel-data. This must be increased whenever an existing template is
 # changed, in order for it to be updated on Elasticsearch upgrade.
-version: 7
+version: 8
 
 component-templates:
   - otel@mappings