Use bash in packaging heredocs (elastic/x-pack-elasticsearch#4145)

In some places in the packaging tests we use heredocs to run some
scripts, for example, under the root user. However, we were running
these heredocs under sh instead of bash. This is confusing since we use
bash everywhere and we end up with syntax in the herdocs that expects
bash but will not necessarily be run under bash. For example, one
circumstance where this arises is the bash syntax [[. This leads to
packaging test failures on some systems (e.g., the debian-8 box) that
are solely due to this sh/bash distinction. We should really be using
bash everywhere, it is the shell that we settled on for all of our
scripts everywhere awhile ago and then we can avoid this confusion. This
commit replaces the usage of sh in the X-Pack packaging tests with bash.

Original commit: elastic/x-pack-elasticsearch@7555bb32c8

qa/vagrant/src/test/resources/packaging/tests/bootstrap_password.bash

@@ -49,7 +49,7 @@ fi
 	    sudo rm -f /tmp/bootstrap.password
     fi
 
-    run sudo -E -u $ESPLUGIN_COMMAND_USER sh <<"NEW_PASS"
+    run sudo -E -u $ESPLUGIN_COMMAND_USER bash <<"NEW_PASS"
 if [[ ! -f $ESCONFIG/elasticsearch.keystore ]]; then
     $ESHOME/bin/elasticsearch-keystore create
 fi
@@ -65,7 +65,7 @@ NEW_PASS
 }
 
 @test "[$GROUP] test bootstrap.password is in setting list" {
-    run sudo -E -u $ESPLUGIN_COMMAND_USER sh <<"NODE_SETTINGS"
+    run sudo -E -u $ESPLUGIN_COMMAND_USER bash <<"NODE_SETTINGS"
 cat >> $ESCONFIG/elasticsearch.yml <<- EOF
 network.host: 127.0.0.1
 http.port: 9200
@@ -92,7 +92,7 @@ NODE_SETTINGS
 	    sudo rm -f /tmp/setup-passwords-output-with-bootstrap
     fi
 
-    run sudo -E -u $ESPLUGIN_COMMAND_USER sh <<"SETUP_OK"
+    run sudo -E -u $ESPLUGIN_COMMAND_USER bash <<"SETUP_OK"
 echo 'y' | $ESHOME/bin/x-pack/setup-passwords auto
 SETUP_OK
     echo "$output" > /tmp/setup-passwords-output-with-bootstrap

qa/vagrant/src/test/resources/packaging/tests/certgen.bash

@@ -152,7 +152,7 @@ start_node_using_package() {
     # The alternative would be to start the master node, use setup-passwords
     # and restart the node once ssl/tls is configured. Or use setup-passwords over
     # HTTPS with the right cacerts imported into a Java keystore.
-    run sudo -E -u $MASTER_USER sh <<"NEW_PASS"
+    run sudo -E -u $MASTER_USER bash <<"NEW_PASS"
 if [[ ! -f $ESCONFIG/elasticsearch.keystore ]]; then
     $ESHOME/bin/elasticsearch-keystore create
 fi
@@ -166,7 +166,7 @@ NEW_PASS
 }
 
 @test "[$GROUP] create instances file" {
-    run sudo -E -u $MASTER_USER sh <<"CREATE_INSTANCES_FILE"
+    run sudo -E -u $MASTER_USER bash <<"CREATE_INSTANCES_FILE"
 cat > /tmp/instances.yml <<- EOF
 instances:
   - name: "node-master"
@@ -233,7 +233,7 @@ CREATE_INSTANCES_FILE
     export ESHOME="$MASTER_HOME"
     export_elasticsearch_paths
 
-    run sudo -E -u $MASTER_USER sh <<"MASTER_SETTINGS"
+    run sudo -E -u $MASTER_USER bash <<"MASTER_SETTINGS"
 cat >> $ESCONFIG/elasticsearch.yml <<- EOF
 node.name: "node-master"
 node.master: true
@@ -316,7 +316,7 @@ MASTER_SETTINGS
     export ESHOME="$DATA_HOME"
     export_elasticsearch_paths
 
-    run sudo -E -u $DATA_USER sh <<"DATA_SETTINGS"
+    run sudo -E -u $DATA_USER bash <<"DATA_SETTINGS"
 cat >> $ESCONFIG/elasticsearch.yml <<- EOF
 node.name: "node-data"
 node.master: false

qa/vagrant/src/test/resources/packaging/tests/setup_passwords.bash

@@ -49,7 +49,7 @@ fi
     run_elasticsearch_service 0
     wait_for_xpack
 
-    run sudo -E -u $ESPLUGIN_COMMAND_USER sh <<"SETUP_AUTO"
+    run sudo -E -u $ESPLUGIN_COMMAND_USER bash <<"SETUP_AUTO"
 echo 'y' | $ESHOME/bin/x-pack/setup-passwords auto
 SETUP_AUTO
     echo "$output" > /tmp/setup-passwords-output