Setup parca-agent for ci-runs

Start collecting profiling data for ci-runs (specifically looking
at longer gating test runs). We want the data for 2 reasons:

 1. See if there are any potential bottlenecks in terms of performance
    that we can see when the jujud and jujud-controller is running.
 2. We can use profile guided optimisations (PGO) from the runs to
    apply to the binaries.

This currently only applies to lxd deployments. For other providers
we will need to install it via cloud-init or bake it into an image.

This is an experiment to see if it's useful or not.

jobs/ci-run/integration/common/test-runner.sh

@@ -32,6 +32,21 @@ while sudo lsof /var/lib/apt/lists/lock 2> /dev/null; do
 done
 sudo apt-get -y update
 
+setup_parca_agent() {
+    # Parca agent is already installed, then skip it.
+    if [ "$(which parca-agent >/dev/null 2>&1)" ]; then
+        return
+    fi
+
+    sudo snap install parca-agent --classic
+    sudo snap set parca-agent metadata-external-labels="machine=ci-run-${{BOOTSTRAP_PROVIDER}}"
+
+    # Hide the setting of the bearer token to the parca agent.
+    set +x
+    sudo snap set parca-agent remote-store-bearer-token="${{PARCA_BEARER_TOKEN}}"
+    set -x
+}
+
 # Issue around installing a snap within a privileged container on a host
 # fails. There is no real work around once privileged and nesting has been
 # set, so retries succeed.
@@ -55,8 +70,18 @@ while [ $attempts -lt 3 ]; do
     if [ ! "$(which microceph >/dev/null 2>&1)" ]; then
         sudo snap install microceph || true
     fi
-    # shellcheck disable=SC2193
-    if [ "${{BOOTSTRAP_PROVIDER:-}}" = "ec2" ]; then
+
+    provider="${{BOOTSTRAP_PROVIDER:-}}"
+    case "$provider" in
+        "lxd" | "lxd-remote" | "localhost")
+            setup_parca_agent || true
+            ;;
+        *)
+            echo "Skipping parca-agent setup for provider: $provider"
+            ;;
+    esac
+
+    if [ "$provider" = "ec2" ]; then
         if [ ! "$(which aws >/dev/null 2>&1)" ]; then
             sudo snap install aws-cli --classic || true
         fi
@@ -72,8 +97,8 @@ while [ $attempts -lt 3 ]; do
         echo -e "[default]\nregion = us-east-1" > "$HOME"/.aws/config
         chmod 600 ~/.aws/*
     fi
-    # shellcheck disable=SC2193
-    if [ "${{BOOTSTRAP_PROVIDER:-}}" = "azure" ]; then
+
+    if [ "$provider" = "azure" ]; then
         if [ ! "$(which az >/dev/null 2>&1)" ]; then
             curl -sL https://aka.ms/InstallAzureCLIDeb | sudo bash
         fi