chore: don't install bats twice (#1574)

`bats` is already installed via npm (this was introduced in [#1252][1]),
so we don't need to install it in the CircleCI build file. The CircleCI
build file was also installing the original bats, while the [`local`][2] and
[`run`][3] packages install a [fork from npm][4].

In addition, I switched the command inside the bats runners from `npx
bats` (which will download/install the latest binary if `yarn install`
was not already run), to `yarn bats`, which will always use the version
specified in the lockfile. This is more consistent with how we run other
commands anyway.

[1]: #1252
[2]: https://github.com/heroku/cli/blob/62085d32f8fa3574bbe03bba707f1f576a9858bf/packages/local/bin/bats-test-runner.js
[3]: https://github.com/heroku/cli/blob/62085d32f8fa3574bbe03bba707f1f576a9858bf/packages/run/bin/bats-test-runner.js
[4]: https://www.npmjs.com/package/bats

.circleci/config.yml

@@ -136,12 +136,6 @@ jobs:
             - v4-yarn-{{ checksum ".circleci/config.yml" }}-{{ checksum "yarn.lock" }}
             - v4-yarn-{{ checksum ".circleci/config.yml" }}
             - v4-yarn
-      - run:
-          name: Installing bats
-          command: |
-            git clone https://github.com/sstephenson/bats.git
-            cd bats
-            ./install.sh /usr/local
       - run:
           name: Installing dependencies
           command: yarn
@@ -290,7 +284,7 @@ workflows:
             - node12-test
             - node10-test
           filters: &master_dev_and_version_tags
-            tags: 
+            tags:
               <<: *version_tags
             branches:
               only:
@@ -317,7 +311,7 @@ workflows:
             - node12-test
             - node10-test
           filters:
-            <<: *only_version_tags 
+            <<: *only_version_tags
       - invalidate_cdn_cache:
           requires:
             - install_scripts

packages/local/bin/bats-test-runner.js

@@ -4,4 +4,4 @@ const os = require('os')
 const {spawn} = require('child_process')
 
 if (os.platform() === 'win32' || os.platform() === 'windows') console.log('skipping on windows')
-else spawn('npx bats test/integration/*.bats', {stdio: 'inherit', shell: true})
+else spawn('yarn bats test/integration/*.bats', {stdio: 'inherit', shell: true})

packages/run/bin/bats-test-runner.js

@@ -4,4 +4,4 @@ const os = require('os')
 const {spawn} = require('child_process')
 
 if (os.platform() === 'win32' || os.platform() === 'windows') console.log('skipping on windows')
-else spawn('npx bats test/integration/*.bats', {stdio: 'inherit', shell: true})
+else spawn('yarn bats test/integration/*.bats', {stdio: 'inherit', shell: true})