[SECENG-669] Remove 'active' attribute for policies

[sagar-connect]

Checklist

=========

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have checked for similar issues and haven't found anything relevant.
• This is not a security issue (which should be reported here: https://circleci.com/security/)
• I have read Contribution Guidelines.

Changes

=======

• Remove 'active' attribute for policies in source (both cmd/api)
• Updated unit-tests
• Updated expected-data.txt (golden tests data)

Rationale

=========
This is in continuation to https://github.com/circleci/policy-service/pull/146

[codecov]

Codecov Report

Merging #750 (e9a09d3) into master (830e7ff) will increase coverage by 0.03%.
The diff coverage is 57.14%.

@@            Coverage Diff             @@
##           master     #750      +/-   ##
==========================================
+ Coverage   31.75%   31.79%   +0.03%     
==========================================
  Files          44       44              
  Lines        5331     5316      -15     
==========================================
- Hits         1693     1690       -3     
+ Misses       3388     3382       -6     
+ Partials      250      244       -6     

Impacted Files	Coverage Δ
api/policy/policy.go	65.45% <40.00%> (+1.54%)	⬆️
cmd/policy/policy.go	81.94% <100.00%> (+2.64%)	⬆️

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