travis: cleanup travis config, scripts and docs

The following commit cleanups any remaining `travis` configurations,
scripts, and documentation.

Signed-off-by: vince-fugnitto <vincent.fugnitto@ericsson.com>

doc/Publishing.md

@@ -30,7 +30,11 @@ One easy way is to use the theia-apps repo CI:
 
 - Make sure that there is no pending build on Theia master, otherwise a new "next" version might be published while we validate the current "next".
 
-- Go in the theia-apps repo [here](https://github.com/theia-ide/theia-apps/commits/master) and identify the latest commit. There should be an icon next to it; either a red X or a green checkmark. Click on it to go the Travis page. There re-trigger the build. We need to make sure that at least the various "next" builds pass CI.If it doesn't, it needs to be fixed before continuing.
+- Go to the `theia-apps` [`actions`](https://github.com/theia-ide/theia-apps/actions?query=workflow%3Aci-cd) and manually trigger a workflow run:
+  - select `run workflow` dropdown
+  - select the `master` branch (should be the default)
+  - click `run workflow`
+- We need to make sure that at least the various "next" builds pass CI.If it doesn't, it needs to be fixed before continuing.
 
 - In case the theia-app images fail CI for reasons not related to the `next` Theia platform extensions (e.g. none of the images currently pass CI including `latest`), a fallback alternative is to build and briefly test one Theia app locally using the `next` version of a good subset of the platform extensions.
 

package.json

@@ -46,8 +46,7 @@
   "scripts": {
     "preinstall": "node-gyp install",
     "postinstall": "node scripts/post-install.js",
-    "prepare": "yarn prepare:travis && yarn prepare:references && yarn prepare:build && yarn prepare:hoisting && yarn download:plugins",
-    "prepare:travis": "node scripts/prepare-travis.js",
+    "prepare": "yarn prepare:references && yarn prepare:build && yarn prepare:hoisting && yarn download:plugins",
     "prepare:references": "node scripts/compile-references.js",
     "prepare:build": "yarn build && run lint && run build \"@theia/example-*\" --stream --parallel",
     "prepare:hoisting": "theia check:hoisted -s",