fix(config): config classloader strategy for different attach scenarios

[andrewazores]

Fixes #486

To test:

Agent:

$ ./mvnw clean spotless:apply install
$ podman build -t quay.io/$MYUSER/cryostat-agent-init:0.5.0-snapshot -f src/main/container/Dockerfile .
$ podman push quay.io/$MYUSER/cryostat-agent-init:0.5.0-snapshot

---

Test applications:
(directly replace $MYUSER in patch - variable substitution probably doesn't work here)

diff --git a/quarkus-agent/build.bash b/quarkus-agent/build.bash
index 20899a8..0209f1a 100755
--- a/quarkus-agent/build.bash
+++ b/quarkus-agent/build.bash
@@ -19,7 +19,7 @@ podman manifest create "${BUILD_IMG}:${BUILD_TAG}"
 
 for arch in ${ARCHS:-amd64 arm64}; do
     echo "Building for ${arch} ..."
-    podman build --platform="linux/${arch}" -t "${BUILD_IMG}:linux-${arch}" -f "${DIR}/src/main/docker/Dockerfile.jvm" "${DIR}"
+    podman build --pull=missing --platform="linux/${arch}" -t "${BUILD_IMG}:linux-${arch}" -f "${DIR}/src/main/docker/Dockerfile.jvm" "${DIR}"
     podman manifest add "${BUILD_IMG}:${BUILD_TAG}" containers-storage:"${BUILD_IMG}:linux-${arch}"
 done
 
diff --git a/wildfly/28/Containerfile b/wildfly/28/Containerfile
index 69286cc..729c573 100644
--- a/wildfly/28/Containerfile
+++ b/wildfly/28/Containerfile
@@ -1,6 +1,6 @@
 ARG agent_version
 
-FROM quay.io/cryostat/cryostat-agent-init:${agent_version} AS agent
+FROM quay.io/$MYUSER/cryostat-agent-init:${agent_version} AS agent
 
 FROM quay.io/wildfly/wildfly:28.0.1.Final-jdk17
 COPY --from=agent /cryostat/agent/cryostat-agent-shaded.jar /opt/cryostat/cryostat-agent.jar
diff --git a/wildfly/28/build.bash b/wildfly/28/build.bash
index fcf585d..383244c 100755
--- a/wildfly/28/build.bash
+++ b/wildfly/28/build.bash
@@ -20,7 +20,7 @@ podman manifest create "${BUILD_IMG}:${BUILD_TAG}"
 
 for arch in "${ARCHS[@]}"; do
     echo "Building for ${arch} ..."
-    podman build --build-arg agent_version="${CRYOSTAT_AGENT_VERSION,,}" --platform="linux/${arch}" -t "${BUILD_IMG}:linux-${arch}" -f "${DIR}/Containerfile" "${DIR}"
+    podman build --pull=missing --build-arg agent_version="${CRYOSTAT_AGENT_VERSION,,}" --platform="linux/${arch}" -t "${BUILD_IMG}:linux-${arch}" -f "${DIR}/Containerfile" "${DIR}"
     podman manifest add "${BUILD_IMG}:${BUILD_TAG}" containers-storage:"${BUILD_IMG}:linux-${arch}"
 done

$ # you may first need to 'podman rmi' and remove existing local container images
$ ./quarkus-agent/build.bash
$ ./wildfly/28/build.bash

---

Cryostat smoketest:

$ ./smoketest.bash -OG -s localstack -t quarkus-cryostat-agent,wildfly-28

Containers should come up. Open https://localhost:8443 in a browser and go to Topology. Both sample applications' Agent instances should be discovered.

Check logs with podman logs compose_quarkus-cryostat-agent_1 or podman logs compose_wildfly-28_1 and ensure that there are no classloader exceptions or null pointer exceptions etc. in the agent startup sequence. HTTP exceptions early on are normal and expected.