fix: make prometheus histogram export cumulative

[AndrewGrachov]

Which problem is this PR solving?

• According to prometheus histogram docs, these histograms should be cumulative. This will allow us to measure estimated quantiles, as we do with raw prometheus

Short description of the changes

• Export histogram as cumulative (e.g

1 to 100 bucket,
1 to 200,
1 to 400 bucket will result in:

1 to 100 bucket ,
2 to 200 bucket
3 to 400 bucket
3 to +inf bucket

[codecov]

Codecov Report

Merging #1570 into master will decrease coverage by 0.24%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1570      +/-   ##
==========================================
- Coverage   93.24%   92.99%   -0.25%     
==========================================
  Files         133      158      +25     
  Lines        3775     4911    +1136     
  Branches      727      992     +265     
==========================================
+ Hits         3520     4567    +1047     
- Misses        255      344      +89     

Impacted Files	Coverage Δ
...ry-exporter-prometheus/src/PrometheusSerializer.ts	96.22% <100.00%> (+0.07%)	⬆️
...-plugin-grpc-js/src/server/clientStreamAndUnary.ts	100.00% <0.00%> (ø)
packages/opentelemetry-plugin-grpc/src/grpc.ts	93.71% <0.00%> (ø)
...opentelemetry-core/src/platform/node/timer-util.ts	50.00% <0.00%> (ø)
packages/opentelemetry-plugin-grpc-js/src/utils.ts	92.30% <0.00%> (ø)
...ackages/opentelemetry-plugin-grpc-js/src/grpcJs.ts	100.00% <0.00%> (ø)
packages/opentelemetry-plugin-http/src/utils.ts	97.36% <0.00%> (ø)
...ces/src/platform/node/detectors/ProcessDetector.ts	100.00% <0.00%> (ø)
packages/opentelemetry-plugin-grpc/src/utils.ts	90.90% <0.00%> (ø)
...ntelemetry-core/src/platform/node/hex-to-base64.ts	100.00% <0.00%> (ø)
... and 19 more