SF: Use port-based IDs for internal displays

Using EDID-based IDs for internal panels is not viable because EDIDs
often contain a unique serial number. This generates a different display
ID for each physical device of the same model, preventing common,
per-model configuration files (e.g., XMLs) from being applied correctly.

This change therefore reverts internal panels to using port-based IDs,
which are consistent across a product line, and reserves the new
EDID-based ID scheme for external displays.

In addition, this approach is preferable for internal displays because:
1. Their port assignments are stable and not expected to change.
2. It guarantees backward compatibility for released devices that rely
   on port-based IDs in their configuration files, avoiding regressions.
3. It preserves cached user settings for the internal display, such as
   accessibility font and display scaling, preventing data loss after an
   update.

Bug: 441113546
Flag: com.android.graphics.surfaceflinger.flags.stable_edid_ids
Test: libsurfaceflinger_unittest && presubmit
Change-Id: Icecb8a52299fb56b37c2c5d17f1c3312c117d010