Rename emergency message to site message.

[dracos]

https://github.com/mysociety/societyworks/issues/3662

[codecov]

Codecov Report

Merging #4450 (f10c60f) into master (423ea16) will decrease coverage by 12.69%.
The diff coverage is n/a.

❗ Current head f10c60f differs from pull request most recent head d4588b3. Consider uploading reports for the commit d4588b3 to get more accurate results

@@             Coverage Diff             @@
##           master    #4450       +/-   ##
===========================================
- Coverage   82.25%   69.56%   -12.69%     
===========================================
  Files         365       41      -324     
  Lines       27667     4873    -22794     
  Branches     4298        0     -4298     
===========================================
- Hits        22758     3390    -19368     
+ Misses       3617     1483     -2134     
+ Partials     1292        0     -1292     

see 325 files with indirect coverage changes

[sallybracegirdle]

Looks good to me!