dovecot: replace solr fts with flatcurve (xapian) (#5680)

* fts-flatcurve: inital implementation

* fts: removed solr from compose.yml

* flatcurve: added heap and proc logic to dovecot

* added logic for update.sh & generate for Flatcurve

* delete old iteration of fts-flatcurve.conf

* updated default fts.conf

* updated .gitignore to exclude fts.conf for further git updates

* Remove autogeneration of fts.conf (disable override)

* cleanup all left solr stuff

* renamed SKIP_FLATCURVE to SKIP_FTS

* cleanup leftovers solr in lang files

* moved lazy_expunge plugin only to mail_plugins

* added fts timeout value

* compose: remove dev image of dovecot

* updated japanese translation

data/web/lang/lang.lv-lv.json

@@ -643,7 +643,6 @@
         "logs": "Žurnāli",
         "architecture": "Arhitektūra",
         "disk_usage": "Diska lietojums",
-        "jvm_memory_solr": "JVM atmiņas lietojums",
         "memory": "Atmiņa",
         "timezone": "Laika josla",
         "uptime": "Darbošanās laiks"