chore(storage): Fix flaky test get_object_context

[shubhangi-google]

PR Fixes following sample failure:

1) Failure:
Files Snippets::get_object_contexts#test_0001_fetches all object contexts [acceptance/files_test.rb:341]:
In stdout.
--- expected
+++ actual
@@ -1,4 +1,4 @@
 "Custom Contexts for path/file_name_9d512d3ea21775ecf8d953f9f31138f6.txt are:
-Key: my-custom-key, Value: my-custom-value
 Key: my-custom-key-2, Value: my-custom-value-2
+Key: my-custom-key, Value: my-custom-value
 "
 1) Failure:
 Files Snippets::list_object_contexts#test_0001_filters out files on the basis of custom context key [acceptance/files_test.rb:351]:
In stdout.
--- expected
+++ actual
@@ -1,2 +1 @@
-"File: path/file_name_11435b5825845b3fdbe1af94a783ea46.txt has context key: my-custom-key
-"
+""

[aandreassa]

@shubhangi-google I already started working on this. #34844