Improve issue templates with guidance about reactions and comments

[Copilot]

This PR improves the GitHub issue templates by adding guidance to help users interact more effectively with issues, similar to the changes made in opentelemetry-collector#13193.

Changes Made

Added a "Tip" dropdown section to both issue templates:

• .github/ISSUE_TEMPLATE/BUG-REPORT.yml
• .github/ISSUE_TEMPLATE/FEATURE-REQUEST.yml

The tip section guides users to:

• Use reactions (👍) to help prioritize issues instead of adding "+1" comments
• Provide useful context in comments rather than "me too" responses
• Learn more about effective issue participation from the OpenTelemetry community guide

Implementation Details

The tip is implemented as a dropdown element that renders as a helpful subtitle in the GitHub issue body, following the same pattern used in the opentelemetry-collector repository. This approach was chosen because GitHub issue forms don't support standalone markdown elements that render in the issue body.

Benefits

• Reduces noise in issues by discouraging low-value comments like "+1"
• Helps maintainers triage issues more efficiently through clear prioritization signals
• Guides community members toward more constructive issue participation
• Maintains consistency with other OpenTelemetry repositories

Fixes #3054.

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[cijothomas]

@copilot This maybe better as a textarea rather than a dropdown, with the contents pre-filled..

[Copilot]

Good suggestion! I've changed both issue templates to use a textarea with pre-filled content instead of a dropdown. This provides better visibility of the guidance text while maintaining the same functionality. Changes made in commit 75ed189.