fix: remove duplicative integration install step

In 0cfe6d8 I introduced a duplicative integration install step when
`context=dev`, not realizing that we have a special case for resolving
integrations in dev mode:

https://github.com/netlify/build/blob/main/packages/build/src/plugins/resolve.js#L189-L195

Returning the tarball location meant we were installing the
integration's packed tarball and then also installing from the pre-pack
build directory. This changeset removes that duplication.

It's... weird that we don't just return the location of a packed npm
package (tarball) and instead have a special case that points at the
pre-pack build artifact directory. This sort of special-cased action at
a distance makes it super hard to understand how this works. I'm going
to circle back on de-confusing this sometime this quarter when I make
the extension build artifact path configurable, which will solve a lot
of testing pain points we currently have.

The failing test I also fix in this changeset was never realistic and
didn't exercise some of the code paths it was supposed to put under
test, so I've updated that test fixture to be realistic.

packages/build/src/install/missing.js

@@ -98,7 +98,7 @@ const getIntegrationPackage = async function ({
       throw new Error(`Failed to build integration. Error:\n\n${e.stack}`)
     }
 
-    return resolve(integrationDir, '.ntli/site/static/packages/buildhooks.tgz')
+    return undefined
   }
 
   return undefined

packages/build/tests/install/fixtures/local_missing_integration/integration/.ntli/build/index.js

@@ -0,0 +1,3 @@
+export const onPreBuild = function () {
+  console.log("Hello world");
+}

packages/build/tests/install/fixtures/local_missing_integration/integration/.ntli/build/manifest.yml

@@ -0,0 +1,2 @@
+name: abc-integration
+inputs: []

packages/build/tests/install/fixtures/local_missing_integration/integration/.ntli/build/package.json

@@ -0,0 +1,7 @@
+{
+  "main": "index.js",
+  "type": "module",
+  "version": "0.0.0",
+  "name": "abc-integration",
+  "dependencies": {}
+}

packages/build/tests/install/fixtures/local_missing_integration/integration/manifest.yml

@@ -1,2 +1,2 @@
-name: test
+name: abc-integration
 inputs: []

packages/build/tests/install/fixtures/local_missing_integration/integration/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "plugin_deps_plugin",
+  "name": "abc-integration",
   "version": "0.0.1",
   "type": "module",
   "scripts": {

packages/build/tests/install/fixtures/local_missing_integration/netlify.toml

@@ -1,5 +1,5 @@
 [[integrations]]
-name = "abc-integration"
+name = "test"
 
 [integrations.dev]
 path = "./integration"

packages/build/tests/install/snapshots/tests.js.md

@@ -1051,7 +1051,6 @@ Generated by [AVA](https://avajs.dev).
       debug: true␊
       repositoryRoot: packages/build/tests/install/fixtures/local_missing_integration␊
       testOpts:␊
-        cwd: ./tests/install/fixtures/local_missing_integration/␊
         pluginsListUrl: test␊
         silentLingeringProcesses: true␊
     ␊
@@ -1070,10 +1069,18 @@ Generated by [AVA](https://avajs.dev).
       dev␊
     ␊
     > Building integrations␊
-       - abc-integration from ./integration␊
+       - test from ./integration␊
     ␊
     > Loading integrations␊
-       - abc-integration␊
+       - test␊
+    ␊
+    test (onPreBuild event)                                       ␊
+    ────────────────────────────────────────────────────────────────␊
+    ␊
+    Hello world␊
+    ␊
+    (test onPreBuild completed in 1ms)␊
+    Build step duration: test onPreBuild completed in 1ms␊
     ␊
     Netlify Build Complete                                        ␊
     ────────────────────────────────────────────────────────────────␊

packages/build/tests/install/tests.js

@@ -153,15 +153,8 @@ test('Install local plugin dependencies: missing plugin in netlify.toml', async
   t.snapshot(normalizeOutput(output))
 })
 
-test('In integration dev mode, install local plugins and install the integration when forcing build', async (t) => {
-  const output = await new Fixture('./fixtures/local_missing_integration')
-    .withFlags({
-      context: 'dev',
-      testOpts: {
-        cwd: './tests/install/fixtures/local_missing_integration/',
-      },
-    })
-    .runWithBuild()
+test.only('In integration dev mode, install local plugins and install the integration when forcing build', async (t) => {
+  const output = await new Fixture('./fixtures/local_missing_integration').withFlags({ context: 'dev' }).runWithBuild()
 
   t.snapshot(normalizeOutput(output))
 })