Fixup generated metrics config

[erikjohnston]

Now looks like:

## Metrics ###

# Enable collection and rendering of performance metrics
enable_metrics: False

# Enable sentry integration
# NOTE: While attempts are made to ensure that the logs don't contain
# any sensitive information, this cannot be guaranteed. By enabling
# this option the sentry server may therefore receive sensitive
# information, and it in turn may then diseminate sensitive information
# through insecure notification channels if so configured.
#sentry:
#    dsn: "..."

# Whether or not to report anonymized homeserver usage statistics.
report_stats: true

Broke by #4632

[richvdh]

lgtm

[codecov-io]

Codecov Report

Merging #4694 into develop will increase coverage by 0.03%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #4694      +/-   ##
===========================================
+ Coverage    75.13%   75.16%   +0.03%     
===========================================
  Files          340      340              
  Lines        34811    34811              
  Branches      5701     5701              
===========================================
+ Hits         26155    26166      +11     
+ Misses        7046     7036      -10     
+ Partials      1610     1609       -1