ci: remove unused dependabot rebase workflow

[nickolas-dimitrakas]

Summary

• Removes the Dependabot Branch Rebase workflow. It only ever targeted the development branch, which AGENTS.md already flags as stale, and forwarded this repo's full release secret set to an external reusable workflow to do it.

Test plan

• Confirmed no other workflow or doc references it.

🤖 Generated with Claude Code

[cursor]

PR Summary

Low Risk
CI workflow cleanup with no impact on SDK code or production build processes.

Overview
Removes the unused dependabot-rebase-branch.yml GitHub Actions workflow, which previously triggered rebasing against the deprecated development branch and forwarded repository secrets to an external reusable workflow.

^{Reviewed by Cursor Bugbot for commit fe2b9b3. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

📦 SDK Size Impact Report

What the SDK adds to a minified release APK.

Measured against an empty baseline app. Unlike the Rokt kit, android-core ships no Compose and no resources, so there is nothing here that a host app would already provide.

mParticle Core SDK

Metric	Target branch	This PR	Change
APK size	119.76 KB	119.76 KB	0 bytes
Download size	117.58 KB	117.58 KB	0 bytes
Dex bytes	213.75 KB	213.75 KB	0 bytes

➡️ SDK size impact change is minimal.

Raw measurements

Target branch:

{"baseline_dex_bytes": 0, "baseline_download_bytes": 2513, "baseline_install_bytes": 7529, "core_dex_bytes": 218884, "core_download_bytes": 122911, "core_install_bytes": 130161}

This PR:

{"baseline_dex_bytes": 0, "baseline_download_bytes": 2512, "baseline_install_bytes": 7528, "core_dex_bytes": 218884, "core_download_bytes": 122910, "core_install_bytes": 130160}

_{Measured fe2b9b3 merged into 38bf857}