Fix multi-stack buildpack deletion in Initialize()

[tnikolova82]

Summary

• Fix Initialize() to handle CF environments with multiple stacks (e.g. cflinuxfs4 + cflinuxfs5) sharing the same buildpack name
• Iterate over /v3/buildpacks resources and issue per-resource delete-buildpack calls with -s <stack> when stack is non-empty

Problem

When CF has both cflinuxfs4 and cflinuxfs5 deployed, buildpacks like ruby_buildpack are registered once per stack. The current code calls cf delete-buildpack -f <name> without -s, causing:

Multiple buildpacks named ruby_buildpack found. Specify a stack name by using a '-s' flag.
FAILED

This breaks all buildpack integration tests on CF environments with multiple stacks.

Fix

Instead of a single delete-buildpack call, loop over all resources from the /v3/buildpacks?names=<name> response. For each resource:

• If stack != "": delete-buildpack -f <name> -s <stack>
• If stack == "": delete-buildpack -f <name> (for any-stack/stackless buildpacks)

History

Version	Behavior	Problem
v0.9.0	Hardcoded -s <stack> on every delete	Fails for stackless/any-stack buildpacks
v0.9.1-v0.9.4	Removed -s flag entirely	Fails when multiple stacks share the same buildpack name
This fix	Conditional -s per resource	Handles all cases correctly

Tests

• Updated "cannot be deleted" failure test (stub now returns a resource so the delete loop is exercised)
• Added "when buildpack exists for multiple stacks" test (expects two -s delete calls)
• Added "when buildpack exists with a single stack" test (expects one -s delete call)
• All 58 tests in internal/cloudfoundry pass

[ivanovac]

lgtm