main/mariadb: quote variables

Partial fix. Subsequent scripts like 'mysqld_safe' still do not handle whitespaces in filenames properly.
7 jobs for !14809 with initd-getconf-fix in 1 minute and 19 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Lint
passed #251286
docker-alpine x86_64
lint

00:00:22

 
  Build
passed #251291
docker-alpine ci-build aarch64
build-aarch64

00:00:33

passed #251292
docker-alpine ci-build armv7
build-armv7

00:00:42

passed #251290
docker-alpine ci-build ppc64le
build-ppc64le

00:00:54

passed #251289
docker-alpine ci-build s390x
build-s390x

00:00:51

passed #251288
docker-alpine ci-build x86
build-x86

00:00:27

passed #251287
docker-alpine ci-build x86_64
build-x86_64

00:00:29