Statically import semconv constants in tests

[trask]

automated via:

for file in $(find instrumentation -name '*Test.java'); do
  echo "Processing $file"

  # stable semconv

  negative_lookbehind='(?<!import static io.opentelemetry.semconv.)'

  for class in "ClientAttributes" "ErrorAttributes" "ExceptionAttributes" "HttpAttributes" "JvmAttributes" "NetworkAttributes" "OtelAttributes" "ServerAttributes" "ServiceAttributes" "TelemetryAttributes" "UrlAttributes" "UserAgentAttributes"; do
    for attr in $(grep -Po "$negative_lookbehind$class\.[A-Z][A-Z][A-Z_]*" $file | sort -u | sed "s/$class\.//"); do
      perl -i -pe "s/$negative_lookbehind$class\.$attr/$attr/" $file
      sed -i "0,/^import/{s/^import/import static io.opentelemetry.semconv.$class.$attr;\nimport/}" $file
    done
  done

  # incubating semconv

  negative_lookbehind='(?<!import static io.opentelemetry.semconv.incubating.)'

  for class in "DbIncubatingAttributes" "HttpIncubatingAttributes" "MessagingIncubatingAttributes"; do
    for attr in $(grep -Po "$negative_lookbehind$class\.[A-Z][A-Z][A-Z_]*" $file | sort -u | sed "s/$class\.//"); do
      perl -i -pe "s/$negative_lookbehind$class\.$attr/$attr/" $file
      sed -i "0,/^import/{s/^import/import static io.opentelemetry.semconv.incubating.$class.$attr;\nimport/}" $file
    done
  done
done

./gradlew spotlessApply

plus one manual rollback: e308dbe

[laurit]

I have usually skipped static imports when there is only 1 usage, but always adding a static import is fine too. At least RpcIncubatingAttributes seems to be missing, could you add static import for these too. Could be done in a separate PR if that is more convenient.