remove deprecated code and BC hacks

[brettmc]

in preparation for RC, removing deprecations and BC hacks so that we have a clean slate for 1.0.0

Fixes #1035
Fixes #1038

[codecov]

Codecov Report

Merging #1099 (6ea089d) into main (82f0c44) will decrease coverage by 0.09%.
The diff coverage is n/a.

❗ Current head 6ea089d differs from pull request most recent head 87c5983. Consider uploading reports for the commit 87c5983 to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1099      +/-   ##
============================================
- Coverage     83.13%   83.05%   -0.09%     
+ Complexity     2202     2149      -53     
============================================
  Files           282      278       -4     
  Lines          6275     6118     -157     
============================================
- Hits           5217     5081     -136     
+ Misses         1058     1037      -21     

Flag	Coverage Δ
7.4	81.66% <ø> (-0.13%)	⬇️
8.0	82.97% <ø> (-0.09%)	⬇️
8.1	83.11% <ø> (-0.09%)	⬇️
8.2	83.11% <ø> (-0.09%)	⬇️

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Files Changed	Coverage Δ
src/SDK/Common/Time/SystemClock.php	64.28% <ø> (+19.28%)	⬆️
src/SDK/Metrics/MeterProviderBuilder.php	0.00% <ø> (ø)
src/SDK/Resource/ResourceInfoFactory.php	100.00% <ø> (+11.36%)	⬆️

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