docker: make `DOCKER_ARMBIAN_BASE_IMAGE` readonly after resolving `DOCKER_ARMBIAN_BASE_COORDINATE_PREFIX`#8925

rpardini wants to merge 1 commit intoarmbian:mainarmbian/build:mainfrom

rpardini:pr/docker-make-DOCKERARMBIANBASEIMAGE-readonly-after-resolving-DOCKERARMBIANBASECOORDINATEPREFIXrpardini/armbian-build:pr/docker-make-DOCKERARMBIANBASEIMAGE-readonly-after-resolving-DOCKERARMBIANBASECOORDINATEPREFIXCopy head branch name to clipboard