Stop retaining runtime packages to reduce storage costs

[lizhineng]

This change prevents the retention of runtime packages after releasing layers on Function Compute, which will significantly reduce our storage costs.

Cost Savings Rationale

Currently, our storage requirements for these packages are substantial:

• Base Storage: Each release consumes ~945MB of storage (45MB/artifact * 21 regions).
• Platform Multiplier: We maintain support for 4 PHP versions (8.1-8.4) across 2 Debian versions (11 and 12), resulting in an 8x multiplier.
• Total Storage: This brings the total storage requirement to 7.56 GB (945MB * 8).

By no longer storing these runtime packages post-release, we can eliminate this storage cost.