refactor: normalize shebang lines across all scripts

Standardize to #!/usr/bin/env bash without extra spaces, replacing
both #!/bin/bash and #! /usr/bin/env bash variants.

Assisted-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Miguel Martín <mmartinv@redhat.com>

Author: mmartinv

tests/bootc/test-bootc-onboarding.sh

@@ -1,4 +1,5 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
 set -eox pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

tests/bootc/test-onboarding.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 set -euox pipefail
 
 # Import util functions

tests/container/test-device-ca-api-v2.sh

@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#!/usr/bin/env bash
 
 set -euo pipefail
 

tests/container/test-device-ca-api.sh

@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#!/usr/bin/env bash
 
 set -euo pipefail
 

tests/container/test-device-ca-rendezvous-trust-v2.sh

@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#!/usr/bin/env bash
 
 set -euo pipefail
 

tests/container/test-device-ca-rendezvous-trust.sh

@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#!/usr/bin/env bash
 
 set -euo pipefail
 

tests/container/test-fsim-download-v2.sh

@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#!/usr/bin/env bash
 
 set -euo pipefail
 

tests/container/test-fsim-download.sh

@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#!/usr/bin/env bash
 
 set -euo pipefail
 

tests/container/test-fsim-upload-v2.sh

@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#!/usr/bin/env bash
 
 set -euo pipefail
 

tests/container/test-fsim-upload.sh

@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#!/usr/bin/env bash
 
 set -euo pipefail