run nightly job that builds with pekko 1.1

[pjfanning]

• refactors the main build to make scala 3.3 part of core tasks instead of separating it out
• the pekko 1.1 job doesn't test with all the JDKs - this is a conscious effort not to go too crazy with all our builds
  • GitHub gives us free builds but they might stop if we get greedy
  • We already test with other JDKs in other r2dbc jobs