t7004: dynamically grab expected state in tests

t7004: dynamically grab expected state in tests

The tests for 'Multiple -l or --list options' and 'trying to delete
tags without params', hardcodes that exactly one or two specific tags
('myhead', 'mytag') exist in the repository.

If other tests are added, modified, or removed earlier in the script,
this expected global state will change, resulting in these tests to fail
for completely unrelated reasons.

Instead of hardcoding the expected tags, dynamically grab the state
of the repository before running the commands under test ('git tag -l'
and 'git tag -d'), and verify that the output matches or remains
unchanged afterward. This keeps the tests independent from the script's
overall state.

Signed-off-by: Siddharth Shrimali <r.siddharth.shrimali@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>