Instead of exit status of `124` (_signifies timeout_), it should fail with `1` (failure) like the others. Handled via using `_run_in_container_bash()` (_`timeout` failure `124` does not propagate and is treated as `1` instead_).
In this case we are waiting on the status of the mail being sent, the pattern provided to `grep` is too specific and results in a timeout. Instead since we only expect the one log entry, match any status and assert the expected pattern afterwards.
This provides a more helpful failure output that informs us that mail was at least processed by Postfix, but the sent status is not what we expected.
### Before
```
✗ [ENV] (POSTFIX_DAGENT) delivers mail to existing account [60327]
(from function `assert_success' in file test/test_helper/bats-assert/src/assert_success.bash, line 42,
in test file test/tests/parallel/set3/mta/lmtp_ip.bats, line 47)
`assert_success' failed
-- command failed --
status : 124
output :
--
```
### After
```
✗ [ENV] (POSTFIX_DAGENT) delivers mail to existing account [1425]
(from function `assert_output' in file test/test_helper/bats-assert/src/assert_output.bash, line 178,
in test file test/tests/parallel/set3/mta/lmtp_ip.bats, line 48)
`assert_output --regexp "${MATCH_LOG_LINE}=sent .* Saved)"' failed
-- regular expression does not match output --
regexp : postfix/lmtp.* status=sent .* Saved)
output : Sep 28 04:12:52 mail postfix/lmtp[721]: 23701B575: to=<user1@localhost.localdomain>, relay=127.0.0.1[127.0.0.1]:24, delay=0.08, delays=0.07/0/0.01/0, dsn=4.2.0, status=deferred (host 127.0.0.1[127.0.0.1] said: 451 4.2.0 <user1@localhost.localdomain> Internal error occurred. Refer to server log for more information. [2023-09-28 04:12:52] (in reply to end of DATA command))
--
```
The expected pattern is logged as `assert_success` confirms a valid match for the log line of interest was found, and we have the mismatched value to debug the failure against.
