jenkins: use osmo-clean-workspace.sh before and after build

See osmo-ci change I2409b2928b4d7ebbd6c005097d4ad7337307dd93 for rationale.

Depends: I2409b2928b4d7ebbd6c005097d4ad7337307dd93
Change-Id: If8aa657c4bf62ef62549fbe9dc15ce3fb018d8d9
diff --git a/contrib/jenkins.sh b/contrib/jenkins.sh
index b815ddd..fb529a4 100755
--- a/contrib/jenkins.sh
+++ b/contrib/jenkins.sh
@@ -19,8 +19,9 @@
 inst="$deps/install"
 export deps inst
 
+osmo-clean-workspace.sh
+
 mkdir "$deps" || true
-rm -rf "$inst"
 
 # Collect configure options for osmo-pcu
 PCU_CONFIG=""
@@ -80,3 +81,5 @@
 DISTCHECK_CONFIGURE_FLAGS="$PCU_CONFIG" AM_DISTCHECK_CONFIGURE_FLAGS="$PCU_CONFIG" \
   $MAKE distcheck \
   || cat-testlogs.sh
+
+osmo-clean-workspace.sh