Trim whitespace before comparing certificate chains

[zrhoffman]

This PR fixes an issue where SSL certificate chain validation fails if the chain does not end with a newline.

This PR also fixes an issue where TO would return a 500 ISE if certificate verification passes.

---

Which Traffic Control components are affected by this PR?

• Traffic Ops

What is the best way to verify this PR?

1. Submit chain that is not modified during verification
2. Make sure verification passes

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

6.1.0

7.0.0

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 #7628 (f6a1a56) into master (dcf6e31) will increase coverage by 0.00%.
The diff coverage is 66.66%.

❗ Current head f6a1a56 differs from pull request most recent head c4a1143. Consider uploading reports for the commit c4a1143 to get more accurate results

@@            Coverage Diff            @@
##             master    #7628   +/-   ##
=========================================
  Coverage     30.12%   30.13%           
  Complexity       98       98           
=========================================
  Files           794      794           
  Lines         84072    84075    +3     
  Branches        907      907           
=========================================
+ Hits          25329    25332    +3     
+ Misses        56613    56612    -1     
- Partials       2130     2131    +1     

Flag	Coverage Δ
golib_unit	48.30% <ø> (+<0.01%)	⬆️
grove_unit	4.60% <ø> (ø)
t3c_unit	5.28% <ø> (ø)
traffic_monitor_unit	21.30% <ø> (ø)
traffic_ops_unit	22.96% <66.66%> (+<0.01%)	⬆️
traffic_portal_v2	73.76% <ø> (-0.03%)	⬇️
traffic_stats_unit	10.14% <ø> (ø)
unit_tests	27.25% <66.66%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
...fic_ops/traffic_ops_golang/deliveryservice/keys.go	31.97% <66.66%> (+0.37%)	⬆️

... and 2 files with indirect coverage changes

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