Remove ListExternalService in favor of internal/db/ExternalServiceStore#List

Created by: asdine

This PR removes ListExternalService from the repo-updater store in favor of internal/db/ExternalServiceStore#List.

Note: By switching to this new method, we lose metrics. Is this acceptable until we add metrics to internal/db stores or should we wait until it is done? cc @tsenart

Created by: sourcegraph-bot

Notifying subscribers in CODENOTIFY files for diff 7599d85c8a39a40636ae0ec2fe76bd2ea77bd66a...97e5c07598c6f4e8823d3af6128891e6b120e398.

Notify	File(s)
@LawnGnome	internal/db/external_services.go internal/db/external_services_test.go
@eseliger	internal/db/external_services.go internal/db/external_services_test.go

Created by: codecov[bot]

Codecov Report

Merging #16822 (7599d85) into main (bfff635) will decrease coverage by 0.00%. The diff coverage is 47.61%.

@@            Coverage Diff             @@
##             main   #16822      +/-   ##
==========================================
- Coverage   52.49%   52.49%   -0.01%     
==========================================
  Files        1703     1703              
  Lines       84831    84833       +2     
  Branches     7606     7721     +115     
==========================================
+ Hits        44530    44531       +1     
+ Misses      36401    36400       -1     
- Partials     3900     3902       +2     

Flag	Coverage Δ
go	51.70% <47.61%> (-0.01%)
integration	29.69% <ø> (ø)
storybook	28.77% <ø> (ø)
typescript	54.38% <ø> (ø)
unit	34.99% <ø> (ø)

Impacted Files	Coverage Δ
cmd/frontend/graphqlbackend/search_commits.go	44.87% <0.00%> (-0.25%)
cmd/frontend/graphqlbackend/search_symbols.go	10.00% <0.00%> (+0.09%)
cmd/frontend/graphqlbackend/search.go	65.66% <58.33%> (-0.40%)
cmd/frontend/graphqlbackend/textsearch.go	67.01% <100.00%> (+0.45%)
.../internal/codeintel/resolvers/graphql/locations.go	83.50% <0.00%> (ø)
...nal/campaigns/resolvers/changeset_apply_preview.go	59.82% <0.00%> (+0.85%)