chore: Sets default make target to agent only [TEST - DO NOT MERGE]

[mfulb]

To support the CodeQL C/C++ scanner autobuild functionality move the default make target to just agent so only C/C++ code it built. This is necessary because the current build env the CodeQL C/C++ scanner uses contains a too old Go compiler to build the daemon target.

Ideally the CodeQL tool/workflow could be configured to just target agent and that would be the recommended long term solution.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (bf0223c) 78.74% compared to head (851ff92) 78.74%.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #830   +/-   ##
=======================================
  Coverage   78.74%   78.74%           
=======================================
  Files         189      189           
  Lines       26370    26370           
=======================================
  Hits        20766    20766           
  Misses       5604     5604           

Flag	Coverage Δ
agent-for-php-7.0	77.60% <ø> (ø)
agent-for-php-7.1	77.33% <ø> (ø)
agent-for-php-7.2	77.89% <ø> (ø)
agent-for-php-7.3	77.91% <ø> (ø)
agent-for-php-7.4	77.58% <ø> (ø)
agent-for-php-8.0	77.67% <ø> (ø)
agent-for-php-8.1	77.63% <ø> (ø)
agent-for-php-8.2	77.41% <ø> (ø)
agent-for-php-8.3	77.41% <ø> (ø)

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