fix(instrumentation-runtime-node): mixin default config in constructor

[satazor]

Which problem is this PR solving?

The constructor of the instrumentation runtime node does not mixin the default config. This means that if I pass an empty object, the eventLoopUtilizationMeasurementInterval will be undefined, which has the side-effect of the configured interval to be near 0.

Short description of the changes

Similarly to all other instrumentations, I've mixed in the default config to make sure default objects are always defined. Please note that the instrumentation file itself didn't have tests, so I haven't added any.

[satazor]

cc @d4nyll @pichlermarc @trentm

[codecov]

Codecov Report

Merging #2036 (b25230d) into main (dfb2dff) will increase coverage by 0.00%.
Report is 15 commits behind head on main.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2036   +/-   ##
=======================================
  Coverage   90.97%   90.98%           
=======================================
  Files         146      145    -1     
  Lines        7492     7454   -38     
  Branches     1502     1488   -14     
=======================================
- Hits         6816     6782   -34     
+ Misses        676      672    -4     

Files	Coverage Δ
...nstrumentation-runtime-node/src/instrumentation.ts	89.18% <100.00%> (ø)

... and 5 files with indirect coverage changes

[d4nyll]

LGTM! Thanks @satazor

[pichlermarc]

thanks 👍