cli/credentials/clear-all: Assume some credentials may be already present and tally it.

[ruda]

There is a situation where credentials are already present in the server and the test is not count it as a base line. Let's tally it.

Note: we are not covering the case where the some previous credential is used by a source, so it will not be deleted and the test will fail anyway. This is a rabbit hole.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 77.24%. Comparing base (d581fce) to head (b54d647).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #494 +/- ## ======================================= Coverage 77.24% 77.24% ======================================= Files 7 7 Lines 624 624 ======================================= Hits 482 482 Misses 142 142 ```

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