tests: postcheck is now in verify

Also introduce 'notexists' for verifying that directory entries do not
exist after a test. Now an explicit supported feature instead of using
"funny

tests: postcheck is now in verify

Also introduce 'notexists' for verifying that directory entries do not
exist after a test. Now an explicit supported feature instead of using
"funny" perl in postcheck.

Closes #15046

show more ...

test1683: remove commented-out check alternatives

Python precheck/postcheck alternatives were included but commented out.
Since these are not used and perl is guaranteed to be available

test1683: remove commented-out check alternatives

Python precheck/postcheck alternatives were included but commented out.
Since these are not used and perl is guaranteed to be available to run
the perl versions anyway, the Python ones are removed.

show more ...

tests: use %LOGDIR to refer to the log directory

This will allow it be set dynamically.

Ref: #10818

curl: add --no-clobber

Does not overwrite output files if they already exist

Closes #7708
Co-authored-by: Daniel Stenberg