Docker/rootless: Remove specific indexer path

[sapk]

Relooking at default configuration we shouldn't define a specific path for indexer of issue especially since it wouldn't be the same as other default indexers paths.

For details on default values: https://github.com/go-gitea/gitea/blob/master/custom/conf/app.example.ini#L447

[codecov-io]

Codecov Report

Merging #13388 into master will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #13388      +/-   ##
==========================================
- Coverage   42.14%   42.14%   -0.01%     
==========================================
  Files         691      691              
  Lines       75966    75966              
==========================================
- Hits        32019    32016       -3     
- Misses      38703    38705       +2     
- Partials     5244     5245       +1     

Impacted Files	Coverage Δ
services/pull/temp_repo.go	26.59% <0.00%> (-3.20%)	⬇️
services/pull/check.go	48.90% <0.00%> (-2.92%)	⬇️
modules/charset/charset.go	70.78% <0.00%> (-2.25%)	⬇️
services/pull/patch.go	53.97% <0.00%> (-1.71%)	⬇️
models/gpg_key.go	53.33% <0.00%> (-0.58%)	⬇️
modules/queue/unique_queue_disk_channel.go	55.38% <0.00%> (+1.53%)	⬆️
services/gitdiff/gitdiff.go	68.54% <0.00%> (+1.81%)	⬆️

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