fix(e2e): use aggressive cleanup threshold (5 min) for pre-run to prevent quota exhaustion (#2798)

The pre-run stale cleanup (added in #2789) used the same 30-minute max_age
as the post-run cleanup. Orphaned instances from recently-failed runs (< 30 min
old) were not cleaned, causing quota exhaustion on DigitalOcean and other clouds.

Pre-run cleanup now uses _CLEANUP_MAX_AGE=300 (5 min) to aggressively reclaim
orphaned e2e instances before provisioning new ones. Post-run cleanup retains
the 30-minute default. All 5 cloud drivers respect the override.

Fixes #2793

Agent: code-health

Co-authored-by: B <6723574+louisgv@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

sh/e2e/lib/clouds/aws.sh

@@ -212,7 +212,7 @@ _aws_cleanup_stale() {
   local region="${AWS_REGION:-us-east-1}"
   local now
   now=$(date +%s)
-  local max_age=1800  # 30 minutes in seconds
+  local max_age="${_CLEANUP_MAX_AGE:-1800}"  # default 30 min; pre-run uses shorter
 
   # List all instances
   local instances_json

sh/e2e/lib/clouds/digitalocean.sh

@@ -287,7 +287,7 @@ _digitalocean_cleanup_stale() {
 
   local now
   now=$(date +%s)
-  local max_age=1800  # 30 minutes in seconds
+  local max_age="${_CLEANUP_MAX_AGE:-1800}"  # default 30 min; pre-run uses shorter
 
   local droplets_json
   droplets_json=$(_do_curl_auth -sf \

sh/e2e/lib/clouds/gcp.sh

@@ -243,7 +243,7 @@ _gcp_cleanup_stale() {
   local project="${GCP_PROJECT:-}"
   local now
   now=$(date +%s)
-  local max_age=1800  # 30 minutes in seconds
+  local max_age="${_CLEANUP_MAX_AGE:-1800}"  # default 30 min; pre-run uses shorter
 
   if [ -z "${project}" ]; then
     log_warn "GCP_PROJECT not set — skipping stale cleanup"

sh/e2e/lib/clouds/hetzner.sh

@@ -229,7 +229,7 @@ _hetzner_teardown() {
 _hetzner_cleanup_stale() {
   local now
   now=$(date +%s)
-  local max_age=1800  # 30 minutes
+  local max_age="${_CLEANUP_MAX_AGE:-1800}"  # default 30 min; pre-run uses shorter
 
   local response
   response=$(_hetzner_curl_auth -sf \

sh/e2e/lib/clouds/sprite.sh

@@ -254,7 +254,7 @@ _sprite_teardown() {
 _sprite_cleanup_stale() {
   local now
   now=$(date +%s)
-  local max_age=1800  # 30 minutes in seconds
+  local max_age="${_CLEANUP_MAX_AGE:-1800}"  # default 30 min; pre-run uses shorter
 
   # List all sprites
   local sprite_output