Updated secret still at earlier content in observers (that labelled them)

## Steps to reproduce

Remove `pytest.mark.xfail` from test `tests/integration/test_charm.py` -> `test_provider_get_set_delete_fields_secrets` for the TLS parameter

## Expected behavior

The secret in `applicatoin/` is rolled to `peek_content()`. It does not return the old value.

## Actual behavior

It is returning the old value instead of the new one.

## Versions

Operating system:

Juju CLI: 3.2.2

Juju agent: 3.1.6

## Log output

Juju debug log: , to be verified with `juju debug-code`

## Additional context