[test][prefix][experiments] Fix integers_echo experiment

The algorithm block was pointing to an invalid algorithm
The analyzers field was missing
The set for the integers dataset was wrong
2 jobs for reorganize_error_related_prefix_content in 20 minutes and 26 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #165974
docker-build
build_linux_36

00:14:56

65.0%
passed #165975
macosx
build_macosx_36

00:20:26

65.0%