chore: remove deprecated Cluster.Http2ProtocolOptions

[michaelbeaumont]

Summary

Closes #2113

[codecov-commenter]

Codecov Report

Merging #4528 (bffc810) into master (177eedf) will decrease coverage by 0.02%.
The diff coverage is 82.85%.

@@            Coverage Diff             @@
##           master    #4528      +/-   ##
==========================================
- Coverage   55.49%   55.47%   -0.03%     
==========================================
  Files         946      946              
  Lines       58230    58235       +5     
==========================================
- Hits        32315    32306       -9     
- Misses      23374    23381       +7     
- Partials     2541     2548       +7     

Impacted Files	Coverage Δ
pkg/xds/bootstrap/template_v3.go	97.31% <82.85%> (-2.01%)	⬇️
pkg/defaults/mesh.go	64.28% <0.00%> (-14.29%)	⬇️
pkg/metrics/store/counter.go	74.54% <0.00%> (-10.91%)	⬇️
pkg/defaults/components.go	85.71% <0.00%> (-3.58%)	⬇️
pkg/core/resources/manager/cache.go	85.71% <0.00%> (+2.59%)	⬆️

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