style: reassign join stream button missing textures

[RominaMarchetti]

What does this PR change?

The Join Stream button looks broken on its idle state for both, the Community result card and Community Card when live streaming.

Test Steps

1. Launch the explorer
2. Open the Communities browser while a Community is live streaming. Click the View All button in the Live Streaming Now section, to see the results card. Check that the Join Stream button, on its idle state, now looks okay.
3. Then click the results card to open the Community card. Check that the Join Stream button, on its idle state, now looks okay.

[github-actions]

Windows and Mac build successful in Unity Cloud! You can find a link to the downloadable artifact below.

Name	Link
Commit	3d7bef4
Logs	https://github.com/decentraland/unity-explorer/actions/runs/18314071418
Download Windows	https://github.com/decentraland/unity-explorer/suites/47082157213/artifacts/4204069048
Download Windows S3	https://explorer-artifacts.decentraland.org/@dcl/unity-explorer/branch/style/join-stream-button-missing-textures/pr-14686-3d7bef4/Decentraland_windows64.zip
Download Mac	https://github.com/decentraland/unity-explorer/suites/47082157213/artifacts/4204030729
Download Mac S3	https://explorer-artifacts.decentraland.org/@dcl/unity-explorer/branch/style/join-stream-button-missing-textures/pr-14686-3d7bef4/Decentraland_macos.zip
Built on	2025-10-07T13:51:26Z

[balducciv]

✔️ PR reviewed and approved by QA on both platforms following instructions.

Regressions for this ticket had been performed in both Windows and Mac to verify that the normal flow is working as expected:

[ ✔️ ] Log In/Log Out
[ ✔️ ] Backpack and wearables in world
[ ✔️ ] Emotes in world and in backpack
[ ✔️ ] Teleport with map/coordinates/Jump In
[ ✔️ ] Chat and multiplayer
[ ✔️ ] Profile card
[ ✔️ ] Camera
[ ✔️ ] Skybox
[ ✔️ ] Settings

Evidence:
Buttons look good on Mac and Windows

Mac:

voice.streaming.mac.mp4

Windows: