build: add CentOS 8 support; drop CentOS 7

Refs: #5040, #5087
Change-Id: I6dcc5e9ee6b4839a6b3f15f1ad6dabf140301ae4
diff --git a/.jenkins.d/30-coverage.sh b/.jenkins.d/30-coverage.sh
index 46d3cf0..0363b9e 100755
--- a/.jenkins.d/30-coverage.sh
+++ b/.jenkins.d/30-coverage.sh
@@ -1,10 +1,5 @@
 #!/usr/bin/env bash
-set -e
-
-JDIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
-source "$JDIR"/util.sh
-
-set -x
+set -ex
 
 if [[ $JOB_NAME == *"code-coverage" ]]; then
     gcovr --object-directory=build \