Jenkinsfile: Use unique boot job names for each branch

Otherwise we overwrite other closures in the map and the last one for
each architecture, kernel ABI and QEMU config wins (dev for dev and PRs
to dev, releng/22.12 for other non-debug QEMU configs and main for other
debug QEMU configs).

Jenkinsfile

@@ -59,10 +59,10 @@ def maybeArchiveArtifacts(params, String os) {
 def addBootJobs(bootJobs, params, String qemuConfig, String architecture, String cheribsdBranch, String suffix="") {
     // For purecap architectures we boot both hybrid and purecap kernels.
     if (architecture.endsWith("-purecap")) {
-        bootJobs["${architecture}-purecap-kernel on ${qemuConfig}"] =
+        bootJobs["${architecture}-purecap-kernel${suffix} on ${qemuConfig}"] =
             { -> bootCheriBSD(params, qemuConfig, "${architecture}-purecap-kernel${suffix}", architecture,
                               'purecap', cheribsdBranch) }
-        bootJobs["${architecture}-hybrid-kernel on ${qemuConfig}"] =
+        bootJobs["${architecture}-hybrid-kernel${suffix} on ${qemuConfig}"] =
             { -> bootCheriBSD(params, qemuConfig, "${architecture}-hybrid-kernel${suffix}", architecture,
                               'hybrid', cheribsdBranch) }
     } else {