Remove the "trace" and "metric" sub-directories from exporters

[MrAlias]

Changes

• The go.opentelemetry.io/otel/exporters/metric/prometheus is renamed to go.opentelemetry.io/otel/exporters/prometheus.
• The go.opentelemetry.io/otel/exporters/trace/jaeger is renamed to go.opentelemetry.io/otel/exporters/jaeger.
• The go.opentelemetry.io/otel/exporters/trace/zipkin is renamed to go.opentelemetry.io/otel/exporters/zipkin.
• Fix the dependabot check that was returning a false-positive check for the /trace and /metric modules.
• Add dependabot entry for the /trace and /metric modules.

Background

All exporters used to be grouped in the metric or trace directory within the exporter directory. When we introduced metric support to the stdout and otlp exporters, which already supported tracing, they did not fit in either directory and were moved up one level. Now that the OTLP exporter is being split internally into trace and metric packages it has forced the question if the trace and metric directory within exporters makes sense.

It does not. It is an added hierarchical level to a package name that does not add useful context. Users of Prometheus know it is used for metrics and users of Jaeger and Zipkin know they are used for tracing.

This is a conclusion the rest of the OpenTelemetry SDKs have also realized. They have all included these exporters at the same directory level:

• https://github.com/open-telemetry/opentelemetry-java/tree/main/exporters
• https://github.com/open-telemetry/opentelemetry-python/tree/main/exporter
• https://github.com/open-telemetry/opentelemetry-js/tree/main/packages
• https://github.com/open-telemetry/opentelemetry-ruby/tree/main/exporter
• https://github.com/open-telemetry/opentelemetry-dotnet/tree/main/src
• https://github.com/open-telemetry/opentelemetry-cpp/tree/main/exporters
• https://github.com/open-telemetry/opentelemetry-php/tree/main/contrib
• https://github.com/open-telemetry/opentelemetry-rust

This change removes duplicate and unneeded hierarchical separation and unifies on a project structure closer matching the rest of the OpenTelemetry community.

[codecov]

Codecov Report

Merging #1992 (1e4c319) into main (7728a52) will decrease coverage by 33.6%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##            main   #1992      +/-   ##
========================================
- Coverage   77.3%   43.6%   -33.7%     
========================================
  Files        162     209      +47     
  Lines       8495   15496    +7001     
========================================
+ Hits        6567    6766     +199     
- Misses      1678    8354    +6676     
- Partials     250     376     +126     

Impacted Files	Coverage Δ
exporters/jaeger/agent.go	73.4% <ø> (ø)
exporters/jaeger/assertsocketbuffersize.go	44.4% <ø> (ø)
exporters/jaeger/env.go	100.0% <ø> (ø)
...internal/gen-go/agent/agent-remote/agent-remote.go	0.0% <ø> (ø)
exporters/jaeger/internal/gen-go/agent/agent.go	6.0% <ø> (ø)
...gen-go/jaeger/collector-remote/collector-remote.go	0.0% <ø> (ø)
exporters/jaeger/internal/gen-go/jaeger/jaeger.go	3.5% <ø> (ø)
...zipkin_collector-remote/zipkin_collector-remote.go	0.0% <ø> (ø)
...rs/jaeger/internal/gen-go/zipkincore/zipkincore.go	0.0% <ø> (ø)
...arty/thrift/lib/go/thrift/application_exception.go	0.0% <ø> (ø)
... and 96 more

[MrAlias]

Just remembered the decision was to deprecate instead of move. Will resubmit this.