Add tests where Branch/Tag assigment is done to a fresh main branch without commits

[nastra]

While working on #2273 I noticed that assigning a branch/tag to a fresh main without any commits didn't work in 0.9.2, thus adding some tests to make sure this works in the latest Nessie version

[codecov]

Codecov Report

Merging #2294 (36e9144) into main (d835229) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main    #2294      +/-   ##
============================================
+ Coverage     83.76%   83.83%   +0.06%     
- Complexity     1843     1847       +4     
============================================
  Files           237      237              
  Lines         10461    10496      +35     
  Branches        734      734              
============================================
+ Hits           8763     8799      +36     
  Misses         1393     1393              
+ Partials        305      304       -1     

Flag	Coverage Δ
java	83.44% <100.00%> (+0.07%)	⬆️
javascript	86.61% <ø> (ø)
python	87.13% <ø> (ø)

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Impacted Files	Coverage Δ
...java/org/projectnessie/jaxrs/AbstractTestRest.java	95.15% <100.00%> (+0.08%)	⬆️
...sioned/persist/tests/AbstractVersionStoreTest.java	96.40% <100.00%> (+0.20%)	⬆️
...nessie/versioned/persist/tx/TxDatabaseAdapter.java	75.00% <0.00%> (+0.21%)	⬆️

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