pelt scheduler: add new tests to validate pelt

[vnarapar]

This PR adds new testcases to validate PELT scheduler

• This validates configs, decay, load tracking, schedutil and different tunables

[smuppand]

@vnarapar please fix the workflow issues

[smuppand]

Since there are multiple files in the PR, I am providing a consolidated review.

1. CI is failing for executable permissions and Shell Lint.
2. All run.sh files use [ -z "$__INIT_ENV_LOADED" ]; please switch to ${__INIT_ENV_LOADED:-}.
3. All run.sh files call check_dependencies but do not check the return value.
4. PELT_decay Method 1 reads /proc/self/sched through grep, so it reads the grep process sched data instead of the shell workload. Please read /proc/$$/sched instead.
5. PELT_sched_debug checks only whether /sys/kernel/debug exists, not whether debugfs is mounted. Please validate debugfs via /proc/mounts.
6. PELT_schedutil uses -ge for “frequency increased”, making the equal-frequency warning path unreachable. Use -gt for increase and handle equality separately.
7. Several scripts write .res and then exit 1. Please exit 0 after writing test FAIL/SKIP results so LAVA can publish the result cleanly.
8. PELT_config still has copy-paste “DMA-BUF” log messages.
9. Some tunables/sysfs entries are kernel-version/config dependent and should not be hard failures unless explicitly documented.
10. YAMLs currently mask cd/run/send-to-lava failures with || true. Please remove unnecessary masking once run.sh result handling is fixed.

After these fixes and runtime evidence on at least one target, this can be reviewed again.