[FEATURE]: Prevent curl dependency from causing hundreds of test targets to appear

[sketch34]

Describe the goal of the feature

Prevent the vscode "Select launch target" dropdown from being populated with hundreds of curl-build test targets.

Is your feature request related to a problem?

After adding dd-trace-cpp many curl-build test targets are present in the vscode "Select launch target" drop-down.

Describe alternatives you've considered

I did a brief search through this repo and in the curl-build cmake files for a solution. I don't think DD_TRACE_BUILD_TESTING is related to this problem.

Additional context

My cmake project is consuming dd-trace-cpp via FetchContent().

if (PX_DD_APM)
  FetchContent_Declare(
    dd-trace-cpp
    GIT_REPOSITORY https://github.com/DataDog/dd-trace-cpp
    GIT_TAG        v2.0.0
    GIT_SHALLOW    ON
    GIT_PROGRESS   OFF
  )

  FetchContent_MakeAvailable(dd-trace-cpp)
endif() # PX_DD_APM

...

set(PX_LINK_LIBS ... $<$<BOOL:${PX_DD_APM}>:dd-trace-cpp::static> ...)

[sketch34]

I found an option CURL_DISABLE_TESTS in out/build/linux-debug/_deps/curl-src/CMakeLists.txt, it appears to have the desired effect. This should probably be in the dd-trace-cpp CMakeLists.txt and defaulted to ON?

if (PX_DD_APM)
  set(CURL_DISABLE_TESTS ON)  # Otherwise curl-build generates hundreds of test targets.

  FetchContent_Declare(
    dd-trace-cpp
    GIT_REPOSITORY https://github.com/DataDog/dd-trace-cpp
    GIT_TAG        v2.0.0
    GIT_SHALLOW    ON
    GIT_PROGRESS   OFF
  )
  
  FetchContent_MakeAvailable(dd-trace-cpp)
endif() # PX_DD_APM