tests: remove core24 snap workarounds (#4761)

Drop core24 workarounds in the spread tests now that `core24` is available on stable.

Signed-off-by: Callahan Kovacs <callahan.kovacs@canonical.com>

spread.yaml

@@ -282,17 +282,6 @@ suites:
      - ubuntu-24.04*
    environment:
      SNAPCRAFT_BUILD_ENVIRONMENT: ""
-   prepare: |
-     # Workaround to be able to test the snaps
-     if snap list core24; then
-       # The already installed case
-       exit 0
-     elif snap install core24; then
-       echo Remove this workaround
-       exit 1
-     else
-       snap install core24 --edge
-     fi
 
  tests/spread/core24-suites/environment/:
    summary: core24 environment tests
@@ -313,17 +302,6 @@ suites:
    summary: core24 patchelf tests
    systems:
      - ubuntu-24.04*
-   prepare: |
-     # Workaround to be able to test the snaps
-     if snap list core24; then
-       # The already installed case
-       exit 0
-     elif snap install core24; then
-       echo Remove this workaround
-       exit 1
-     else
-       snap install core24 --edge
-     fi
 
  # General, core suite
  tests/spread/general/: