Remove Dependabot docker ecosystem entry

[rajathagasthya]

Description

Renovate already manages the base images in docker/Dockerfile and
docker/Dockerfile.devel, and intentionally skips digest-only updates
for builder-stage images. The Dependabot docker entry kept opening
those digest-only PRs (e.g. #2823, #2813) and duplicated distroless/cc
bumps (#2822 vs #2825).

Checklist

• No secrets, sensitive information, or unrelated changes
• Lint checks passing (make lint)
• Generated assets in-sync (make validate-generated-assets)
• Go mod artifacts in-sync (make validate-modules)
• Test cases are added for new code paths

Testing

Config-only change to .github/dependabot.yml; no code paths affected.

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📥 Commits

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• .github/dependabot.yml

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• .github/dependabot.yml

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📝 Walkthrough

Walkthrough

Removed the Dependabot configuration for Docker updates, including its daily schedule and Golang ignore rule. Go module and GitHub Actions update configurations remain unchanged.

Merge Risk: ⚪ Minimal · up to b5c57

This is a localized configuration cleanup that removes duplicate Docker update automation without changing product code or runtime behavior. No actionable merge-blocking risk remains beyond normal checks and review.

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