android_zoom.py: fix Zoom 6.x control detection and harden the join flow

[Narayana-CT]

Summary

Android participants running Zoom 6.x joined meetings but never turned their
camera on, so they contributed no uplink video to the results while the run
still exited 0 and produced a clean-looking report. This branch fixes that and
makes the join path more robust.

Three commits, all in py-scripts/real_application_tests/zoom_automation/android_zoom.py:

Commit	Change
cff162b1	Pre-grant Zoom's runtime permissions over adb before joining
4fe2c89e	Target the Zoom package on the meeting intent; raise the preview-screen timeout; explain the toolbar setting when A/V cannot be toggled
6bb72fde	Match in-meeting control labels by prefix instead of exact equality

Root cause of the main bug

Zoom labels the same in-meeting controls differently between releases:

Zoom	content-desc for the mic button
7.x	Mute my audio, button
6.x	Mute my audio Button 1 of 13

6.x drops the comma, capitalises Button, appends N of 13, and labels Leave
through text= with an empty content-desc. The matchers used exact equality
against the 7.x strings only, so on 6.x clients:

• get_audio_control_info() / get_video_control_info() returned None
• enable_audio_video() logged "button not visible" for all 15 retries and left
  the camera off
• get_leave_control_info() found nothing and fell through to pressing back

This was confirmed by dumping the live UI hierarchy from a 6.6.0 device while it
sat in a meeting with the toolbar visible: the buttons were present and
readable; only the string comparison failed. Enabling Zoom's
"Always show meeting controls" does not help, because visibility was never the
problem.

_control_label() now reads content-desc, falls back to text when that is
empty, and callers compare on the label prefix, so both layouts resolve.

Other changes

• Permission pre-granting reads the runtime permissions the package actually
  declares on that device, so one code path covers every API level, and sets
  SYSTEM_ALERT_WINDOW through appops since pm grant cannot. This replaces
  clicking the "While using the app" / "Allow" dialogs.
• Meeting intent now names the Zoom package, so the deep link cannot be
  captured by a browser or a chooser dialog.
• Preview-screen timeout raised 5s to 30s. This is load-bearing: one handset
  reached the preview screen only after 26 seconds and would have failed at 5s.

Testing

Three consecutive 2-minute runs on the interop testbed, host plus five Android
devices, covering Zoom 6.5.12, 6.6.0, 7.0.4, 7.1.6 and Android SDK 31, 33, 36
(OPPO CPH2725, Pixel 4a x2, Samsung SM-F415F, Samsung SM-A217F).

Every participating device joined, reported both audio and video enabled, and
left without falling back to the back key. Before this change, only the two
Zoom 7.x devices managed that; the three 6.x devices failed all 15 A/V retries.
Both label variants were exercised in the logs.

Verified with:

python3 lf_interop_zoom.py --duration 2 \
    --lanforge_ip 192.168.245.117 \
    --signin_email <zoom_email> --signin_passwd <zoom_passwd> \
    --participants 6 --audio --video \
    --upstream_port <upstream_ip> \
    --zoom_host 1.13 \
    --resources 1.13,1.12,1.15,1.16,1.22,1.25 \
    --api_stats_collection --env_file .env

Known limitations

• Fresh OPPO/ColorOS devices have no permission fallback. That ROM refuses
  adb pm grant, and this branch removes the UI dialog handling that used to
  cover it. Devices where the mic/camera prompts were already accepted once are
  unaffected, which is why the OPPO in the testbed still passes.