[Backport 5.4] scylla_io_setup: ensure correct RLIMIT_NOFILE for iotune

[mergify[bot]]

The default limit of open file descriptors per process may be too small for iotune on certain machines with large number of cores.

In such case iotune reports failure due to unability to create files or to set up seastar framework.

This change configures the limit of open file descriptors before running iotune to ensure that the failure does not occur.

The limit is set via 'resource.setrlimit()' in the parent process. The limit is then inherited by the child process.

(cherry picked from commit 0be690d6a2e9f40d38cf1c06cc739b614dfef779)

Refs #18546

[scylladb-promoter]

:green_circle: CI State: SUCCESS

:white_check_mark: - Build :white_check_mark: - dtest :white_check_mark: - Unit Tests

Build Details:

• Duration: 7 hr 16 min
• Builder: i-01ca3c5e6b7130d09 (m5ad.8xlarge)

[mykaul]

@scylladb/scylla-maint - please review and merge.

[yaronkaikov]

@mykaul it's already promoted, for now it should be closed manually (when i will send a patch to update the label i will automatically close the PR as well

Closed via https://github.com/scylladb/scylladb/commit/28d0fc1b6b24fd36cae28cd2ea4d39a9df6e90cb