[Data-Aware WC] Fix Statistics Processing for Data Aware Methods

[anzr299]

Changes

Fix logic to sample activation values from the collected statistics which resolves a bug.

Reason for changes

An error was introduced with the addition of SE support for 3D weights #3706. This was spotted by the failing test https://github.com/openvinotoolkit/nncf/actions/runs/19549771001

Related tickets

Tests

1. Extended Scale estimation test test_scale_estimation() in tests/cross_fw/test_templates/template_test_weights_compression.py to include the case where calibration dataset size > scale estimation subset size
2. Added test_process_stats in weights compression template test for testing the process_stats function.

Example Test: https://github.com/openvinotoolkit/nncf/actions/runs/19580896526
WC Conformance Test: https://github.com/openvinotoolkit/nncf/actions/runs/19577215441

Precision Type	Filter	Value	Stderr
INT4 SYM Per-Channel (with Scale estimation) After Fix	flexible-extract	0.61	0.0490
	strict-match	0.40	0.0492
INT4 SYM Per-Channel (with Scale estimation) Before fix	flexible-extract	0.66	0.0476
	strict-match	0.38	0.0488
INT4 SYM Per-Channel	flexible-extract	0.77	0.0423
	strict-match	0.28	0.0451
FP16	flexible-extract	0.91	0.0288
	strict-match	0.86	0.0349

[AlexanderDokuchaev]

Please add a unit test for process_stats function