fix: remove unused TestContext (#1013)

The function `WithTestContext` is never called in the project, and
there is just one usage of `TestContext`, inside one of our loggers

Co-authored-by: Casey Lee <[email protected]>
Co-authored-by: Björn Brauer <[email protected]>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

pkg/common/testflag.go

@@ -1,20 +0,0 @@
-package common
-
-import (
-	"context"
-)
-
-type testFlagContextKey string
-
-const testFlagContextKeyVal = testFlagContextKey("test-context")
-
-// TestContext returns whether the context has the test flag set
-func TestContext(ctx context.Context) bool {
-	val := ctx.Value(testFlagContextKeyVal)
-	return val != nil
-}
-
-// WithTextContext sets the test flag in the context
-func WithTestContext(ctx context.Context) context.Context {
-	return context.WithValue(ctx, testFlagContextKeyVal, true)
-}