[2.3.0] Checkmk Werk 16887 created: mk_job: MK_VARDIR defaults not being set in bakery

[//]: # (werk v2) # mk_job: MK_VARDIR defaults not being set in bakery key | value ---------- | --- compatible | yes version | 2.3.0p12 date | 2024-07-26T05:47:27+00:00 level | 1 class | fix component | checks edition | cre Due to a different way to set in `MK_VARDIR` in `mk_job`, default values would not be baked into `mk_job` and derivates. This change adds a replacement rule for the way `MK_VARDIR` gets assigned in `mk_job` and also separates assignment and export in order to avoid known problems with Solaris.