fix(infiniband): skip sysfs reads for excluded devices

[pujitha24]

Motivation:
--collector.infiniband.device-exclude (and device-include) correctly
filtered excluded devices out of emitted metrics, but the collector's
Update() called sysfs.FS.InfiniBandClass(), which eagerly parses every
device under /sys/class/infiniband -- including reading each port's
counter files -- before the device filter is ever applied. On hosts
with firmware-managed restricted ports, reading those counter files
can trigger a firmware command that fails and floods the kernel log,
even though the offending device was explicitly excluded.

Approach:
Enumerate device names first via sysfs.FS.InfiniBandClassDevices(),
which only lists directory entries and performs no attribute or
counter reads. Apply the existing device filter against the name,
and only call sysfs.FS.InfiniBandDevice(name) -- which does the
actual sysfs reads -- for devices that pass the filter. This does
not change emitted metrics for included devices; it only avoids
touching excluded devices' sysfs files at all.

Validation:
Added TestInfiniBandCollectorSkipsSysfsReadsForExcludedDevices, which
builds a synthetic sysfs tree with a healthy device and a device
missing its required fw_ver file (simulating a device whose
attributes/counters cannot be read), then excludes the broken device
via device-exclude and asserts Update() succeeds and only the
included device's metrics are emitted.

Report: #3823
Signed-off-by: Pujitha Paladugu 10557236+pujitha24@users.noreply.github.com
Assisted-by: claude-sonnet-5 (via Claude Code)