Add mvn settings for a lone mvn command which lacked one

[kshultzCB]

While working on some other things, it was brought to my attention by @imonteroperez that the line I've modified was lacking a -s "{MVN_SETTINGS_FILE}" like the others around it. Without this, if a particular PCT run is relying upon those settings for different repository locations and the like, this line will fail.

For example:

+ echo 'Located custom plugin sources on the volume'
Located custom plugin sources on the volume
+ mkdir /pct/tmp/localCheckoutDir/undefined
+ cp -r /pct/plugin-src/. /pct/tmp/localCheckoutDir/undefined
+ cd /pct/tmp/localCheckoutDir/undefined
+ mvn -B clean
Picked up JAVA_TOOL_OPTIONS: -Xmx1g
[INFO] Scanning for projects...
[INFO] Downloading from central: https://repo.maven.apache.org/maven2/com/cloudbees/jenkins/plugins/jenkins-plugins/80/jenkins-plugins-80.pom
[ERROR] [ERROR] Some problems were encountered while processing the POMs:
[FATAL] Non-resolvable parent POM for com.cloudbees.jenkins.plugins.pipeline:some-plugin:0.9-SNAPSHOT: Could not find artifact com.cloudbees.jenkins.plugins:jenkins-plugins:pom:80 in central (https://repo.maven.apache.org/maven2) and 'parent.relativePath' points at no local POM @ line 4, column 13

[kshultzCB]

CI failures look like something download related.

[2020-03-20T18:00:56.110Z] + curl -sL http://mirrors.jenkins.io/war-stable/2.164.1/jenkins.war --output jenkins.war

[2020-03-20T18:00:56.679Z] + echo 65543f5632ee54344f3351b34b305702df12393b3196a95c3771ddb3819b220b jenkins.war

[2020-03-20T18:00:56.679Z] + sha256sum --check

[2020-03-20T18:00:56.679Z] jenkins.war: FAILED

[2020-03-20T18:00:56.679Z] sha256sum: WARNING: 1 computed checksum did NOT match

script returned exit code 1

I'm doing the close/reopen dance to trigger another attempt.

[kshultzCB]

Let's try a >10 second beat drop.

[kshultzCB]

One more beat drop.