t3c: strategies.yaml hash_key only for consistent_hash

[traeak]

The t3c strategies.yaml file when generating a strategy always populates the hash_key yaml field although it only applies to consistent_hash policy.

Currently with this configuration ATS 9.2 will bump into the unexpected hash_key field for non consistent_hash policy and abort loading the strategies file entirely.

Note the ATS docs here where hash_key only applies to consistent_hash policy.
https://docs.trafficserver.apache.org/en/latest/admin-guide/files/strategies.yaml.en.html?highlight=strategies#strategies-definitions

---

Which Traffic Control components are affected by this PR?

• Traffic Control Cache Config (t3c, formerly ORT)

What is the best way to verify this PR?

Create DS services, one with consistent_hash and another with round robin.
Run t3c to generate strategies.yaml
Ensure that the DS with consistent_hash policy also has a hash_key key/value
Ensure that the DS with round robin (rr_strict or rr_ip) does not have a hash_key entry.

As a bonus, drop the strategies.yaml file into an ats config directory, fire up ATS9.2 and verify that the strategies.yaml file loads without generating an error.

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

7.1.0

PR submission checklist

• This PR has tests
• This PR has documentation bug fix
• 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 #7204 (4624888) into master (bf8e18f) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master    #7204   +/-   ##
=========================================
  Coverage     28.37%   28.37%           
  Complexity       98       98           
=========================================
  Files           617      617           
  Lines         69197    69202    +5     
  Branches         90       90           
=========================================
+ Hits          19634    19639    +5     
  Misses        47754    47754           
  Partials       1809     1809           

Flag	Coverage Δ
golib_unit	53.10% <100.00%> (+0.02%)	⬆️
grove_unit	4.60% <ø> (ø)
t3c_generate_unit	24.96% <ø> (ø)
traffic_monitor_unit	20.43% <ø> (ø)
traffic_ops_unit	19.81% <ø> (ø)
traffic_stats_unit	10.41% <ø> (ø)

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

Impacted Files	Coverage Δ
lib/go-atscfg/strategiesdotconfig.go	91.78% <100.00%> (+0.03%)	⬆️
lib/go-atscfg/ipallowdotyaml.go	71.61% <0.00%> (+0.25%)	⬆️
lib/go-atscfg/ipallowdotconfig.go	69.62% <0.00%> (+0.28%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[jpappa200]

This looks good to me, just need to remove the typo in CHANGELOG.md