Fix some golangci-lint errors in campaigns code

Created by: eseliger

From time to time I get annoyed by the yellow squiggly lines, so I thought it's about time for another round of fixing some of them, so here we are.

Created by: sourcegraph-bot

Notifying subscribers in CODENOTIFY files for diff f6a6fef0ba867cbae7db23b1ded3eaaa7843936f...2aa263a3f6444feafc91689a02ef02c8a5d35cda.

Notify	File(s)
@LawnGnome	enterprise/internal/campaigns/background.go enterprise/internal/campaigns/service/service_apply_campaign.go enterprise/internal/campaigns/store/campaign_specs.go enterprise/internal/campaigns/store/campaigns.go enterprise/internal/campaigns/store/changeset_events.go enterprise/internal/campaigns/store/codehost.go enterprise/internal/campaigns/store/store.go

Created by: codecov[bot]

Codecov Report

Merging #17791 (2aa263a) into main (f6a6fef) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main   #17791   +/-   ##
=======================================
  Coverage   45.47%   45.48%           
=======================================
  Files        1722     1722           
  Lines       86337    86329    -8     
  Branches     7668     7668           
=======================================
+ Hits        39266    39267    +1     
+ Misses      43178    43172    -6     
+ Partials     3893     3890    -3     

Flag	Coverage Δ		*Carryforward flag
go	49.98% <100.00%> (+<0.01%)
typescript	34.50% <ø> (ø)		Carriedforward from f6a6fef
unit	34.50% <ø> (ø)		Carriedforward from f6a6fef

*This pull request uses carry forward flags. Click here to find out more.

Impacted Files	Coverage Δ
...erprise/internal/campaigns/store/campaign_specs.go	84.50% <ø> (ø)
...prise/internal/campaigns/store/changeset_events.go	82.45% <ø> (ø)
enterprise/internal/campaigns/store/codehost.go	83.33% <ø> (ø)
enterprise/internal/campaigns/store/store.go	64.15% <ø> (+3.43%)
...ternal/campaigns/service/service_apply_campaign.go	74.64% <100.00%> (-0.36%)
enterprise/internal/campaigns/store/campaigns.go	91.08% <100.00%> (+2.26%)
.../internal/codeintel/resolvers/graphql/locations.go	85.56% <0.00%> (+2.06%)