fix: remove npm cache from CTC workflows to support pnpm/yarn repos

ctcOpen.yml and ctcClose.yml set actions/setup-node `cache: npm`, which
requires an npm lockfile to compute its cache key. Consumer repos on pnpm
or yarn have no package-lock.json, so setup-node fails with "Dependencies
lock file is not found" and the CTC job dies before it ever runs.

The only npm operation in these jobs is the one-off global install of
@salesforce/change-case-management, which the cache does not key on, so it
provides no benefit here. Dropping `cache: npm` lets the CTC legs run for
npm, yarn, and pnpm consumers alike.

Author: mohanraj-r

.github/workflows/ctcClose.yml

@@ -20,7 +20,8 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: lts/*
-          cache: npm
+          # No `cache: npm`: it requires an npm lockfile and so hard-fails on
+          # pnpm/yarn consumer repos; the CTC CLI below is a one-off global install.
       - run: npm install -g @salesforce/change-case-management --omit=dev
       - id: ctc
         run: |

.github/workflows/ctcOpen.yml

@@ -20,7 +20,8 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: lts/*
-          cache: npm
+          # No `cache: npm`: it requires an npm lockfile and so hard-fails on
+          # pnpm/yarn consumer repos; the CTC CLI below is a one-off global install.
 
       - run: npm install -g @salesforce/change-case-management --omit=dev