fi-0121: Deprecated attribute {:#fi-0121}

Some official attributes are deprecated and should no longer be used:

{% include “docs/reference/fidl/language/error-catalog/label/_bad.md” %}

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="tools/fidl/fidlc/tests/fidl/bad/fi-0121.test.fidl" exclude_regexp="\/\/ (Copyright 20|Use of|found in).*" %}

The fix depends on why the attribute was deprecated. For example, the error message might say to use a different attribute instead. In this case, we can just remove the attribute:

{% include “docs/reference/fidl/language/error-catalog/label/_good.md” %}

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="tools/fidl/fidlc/tests/fidl/good/fi-0121.test.fidl" exclude_regexp="\/\/ (Copyright 20|Use of|found in).*" %}