[mdatagen] fix generated comp test for extensions and unused imports …

…in templates (open-telemetry#10477)

#### Description

When upgrading beyond `v0.101.0` of `mdatagen` I ran into issues
upgrading when running `golanglint-ci` because of unused imports.
Namely, in `component_tests` the `component` was removed from [this
commit](https://github.com/open-telemetry/opentelemetry-collector/compare/v0.101.0...v0.102.0?diff=split&w=#diff-abf7cf477183f2c7e2f9425655bea3a2e2060eaba8fb6aa9c9a9558017c21f1e)
which was not caught by tests (it appears we only test receiver
components & not others). The logic that generates tests for extensions,
where I caught this error, ends up with a `generated_component_test`
that does not use `component` in the package at all. I would've thought
the contrib repo would've detected this issue since they also use
`mdatagen` and there are extensions there + golangci-lint. I haven't dug
into the why it wasn't caught there yet.

> This is just a quick fix for extensions. I suspect this issue may pop
up in other components as time goes on. Long term is more tests for
other components.

#### Testing
I ran this locally against my own repo where the issue originally showed
& ensured the value would be templated out appropriately.


![image](https://github.com/open-telemetry/opentelemetry-collector/assets/25961386/f82abb28-7b78-401f-8875-cb2c66f5cf9b)

.chloggen/fix-component-tests.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: mdatagen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: fix generated comp test for extensions and unused imports in templates
+
+# One or more tracking issues or pull requests related to the change
+issues: [10477]
+
+# (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:
+
+# 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: []

cmd/mdatagen/templates/component_test.go.tmpl

@@ -16,7 +16,7 @@ import (
 	{{- end }}
 
 	"github.com/stretchr/testify/require"
-	{{- if not (and .Tests.SkipLifecycle .Tests.SkipShutdown) }}
+	{{- if and (not (and .Tests.SkipLifecycle .Tests.SkipShutdown)) (not isExtension) }}
 	"go.opentelemetry.io/collector/component"
 	{{- end }}
 	"go.opentelemetry.io/collector/component/componenttest"

cmd/mdatagen/templates/telemetry_test.go.tmpl

@@ -7,8 +7,6 @@ import (
 
 	"github.com/stretchr/testify/require"
 	"go.opentelemetry.io/otel/metric"
-	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	embeddedmetric "go.opentelemetry.io/otel/metric/embedded"
 	noopmetric "go.opentelemetry.io/otel/metric/noop"
 	"go.opentelemetry.io/otel/trace"