Only copy runtime policies when enabled

[lebauce]

What does this PR do?

Only copy the runtime security policies when runtime security is enabled

Motivation

When runtime security is not enabled, one init container fails:

$ k logs datadog-agent-kmr2q -c init-volume -n datadog
cp: cannot stat '/etc/datadog-agent-runtime-policies/*': No such file or directory

[github-actions]

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[codecov-commenter]

Codecov Report

Merging #328 (55def66) into main (0a9f32b) will increase coverage by 0.57%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #328      +/-   ##
==========================================
+ Coverage   58.49%   59.07%   +0.57%     
==========================================
  Files          60       60              
  Lines        6371     6370       -1     
==========================================
+ Hits         3727     3763      +36     
+ Misses       2370     2337      -33     
+ Partials      274      270       -4     

Flag	Coverage Δ
unittests	59.07% <100.00%> (+0.57%)	⬆️

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

Impacted Files	Coverage Δ
controllers/datadogagent/utils.go	84.26% <100.00%> (+2.63%)	⬆️

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