Removed TryIfModifiedSinceQuery from servicecategories.go and reused from ims.go

[jagan-parthiban]

Closes: No related Issues

---

Which Traffic Control components are affected by this PR?

• Traffic Ops

What is the best way to verify this PR?

The Get request to service_category api with If-Modified-Since should return 304.

curl --request GET \
  --url https://localhost:8443/api/5.0/service_categories \
  --header 'If-Modified-Since: Mon, 04 Jul 2024 18:00:00 IST'

If this is a bugfix, which Traffic Control versions contained the bug?

• 7.0.1

PR submission checklist

• This PR has tests
• This PR has documentation
• This PR has a CHANGELOG.md entry
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)

[codecov]

Codecov Report

Merging #7623 (30a5dcb) into master (c36c7b0) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master    #7623      +/-   ##
============================================
- Coverage     30.13%   30.12%   -0.01%     
  Complexity       98       98              
============================================
  Files           794      794              
  Lines         84106    84067      -39     
  Branches        907      907              
============================================
- Hits          25344    25329      -15     
+ Misses        56634    56608      -26     
- Partials       2128     2130       +2     

Flag	Coverage Δ
golib_unit	48.29% <ø> (ø)
grove_unit	4.60% <ø> (ø)
t3c_unit	5.28% <ø> (ø)
traffic_monitor_unit	21.30% <ø> (ø)
traffic_ops_integration	69.42% <ø> (ø)
traffic_ops_unit	22.95% <100.00%> (-0.02%)	⬇️
traffic_portal_v2	73.78% <ø> (ø)
traffic_stats_unit	10.14% <ø> (ø)
unit_tests	27.25% <100.00%> (-0.01%)	⬇️
v3	57.79% <ø> (ø)
v4	79.18% <ø> (ø)
v5	78.63% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ic_ops_golang/servicecategory/servicecategories.go	10.21% <100.00%> (-6.46%)	⬇️

... and 1 file with indirect coverage changes

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[rimashah25]

LGTM