fix: use hash to compare user metadata value (#10749)

# Which Problems Are Solved

Depending on the metadata values (already existing), the newly created
index (#10415) cannot be created or error in the future.

# How the Problems Are Solved

- Create the index using `sha256` and change the query to use sha256 as
well when comparing bytes values such as user_metadata.
- Added a setup step to cleanup potentially created index on
`projections.user_metadata5`

# Additional Changes

None

# Additional Context

- relates to #10415
- requires backport to v4.x

(cherry picked from commit 57e8033b6e)

internal/query/projection/user_metadata.go

@@ -49,8 +49,8 @@ func (*userMetadataProjection) Init() *old_handler.Check {
 		},
 			handler.NewPrimaryKey(UserMetadataColumnInstanceID, UserMetadataColumnUserID, UserMetadataColumnKey),
 			handler.WithIndex(handler.NewIndex("resource_owner", []string{UserGrantResourceOwner})),
-			handler.WithIndex(handler.NewIndex("metadata_key", []string{UserMetadataColumnKey})),
-			handler.WithIndex(handler.NewIndex("metadata_value", []string{UserMetadataColumnValue})),
+			handler.WithIndex(handler.NewIndex("key", []string{UserMetadataColumnKey})),
+			handler.WithIndex(handler.NewIndex("value", []string{"sha256(" + UserMetadataColumnValue + ")"})),
 		),
 	)
 }