chore: update to OTel 0.15.0

[Flarna]

Which problem is this PR solving?

Fixes: #311
Fixes: #309
Fixes: #314
Fixes: #308

Short description of the changes

Update all dependencies to 0.15.0 and adapt code to changed APIs.

[codecov]

Codecov Report

Merging #315 (63c28ef) into master (6fab815) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #315   +/-   ##
=======================================
  Coverage   95.41%   95.41%           
=======================================
  Files         115      115           
  Lines        6087     6090    +3     
  Branches      592      590    -2     
=======================================
+ Hits         5808     5811    +3     
  Misses        279      279           

Impacted Files	Coverage Δ
packages/opentelemetry-host-metrics/src/metric.ts	100.00% <ø> (ø)
...ages/opentelemetry-host-metrics/src/BaseMetrics.ts	57.57% <100.00%> (+1.32%)	⬆️
...entelemetry-instrumentation-graphql/src/graphql.ts	92.25% <100.00%> (+0.11%)	⬆️
...opentelemetry-instrumentation-graphql/src/utils.ts	95.20% <100.00%> (+0.02%)	⬆️
...s/node/opentelemetry-plugin-pg-pool/src/pg-pool.ts	88.88% <100.00%> (ø)
.../opentelemetry-plugin-pg-pool/test/pg-pool.test.ts	89.60% <100.00%> (-0.09%)	⬇️
plugins/node/opentelemetry-plugin-pg/src/pg.ts	91.52% <100.00%> (ø)
...ugins/node/opentelemetry-plugin-pg/test/pg.test.ts	94.34% <100.00%> (-0.03%)	⬇️
...lugin-react-load/src/BaseOpenTelemetryComponent.ts	97.47% <100.00%> (+0.48%)	⬆️
...tor-grpc-census-binary/src/GrpcCensusPropagator.ts	97.43% <100.00%> (ø)
... and 20 more

[vmarchaud]

lgtm, just need CI green

[Flarna]

pushed a fixup to get the document load test green. But I must admit that I have no idea why it failed and if the changes I did to get it green are correct.

@obecny I think you created the plugin initially. Would be nice if you could take a look.

[Flarna]

Please note also that I haven't touched examples here because they refer to concrete versions of packages. Therefore I think this should be done via a separate PR short before creating the next release.

[johnbley]

lgtm

[obecny]

lgtm

[obecny]

pushed a fixup to get the document load test green. But I must admit that I have no idea why it failed and if the changes I did to get it green are correct.

@obecny I think you created the plugin initially. Would be nice if you could take a look.

it failed because there was also a change in web so one more resource is being reported now, fix is fine