Build/Test Tools: Remove the TravisCI configuration file.

In [49162], GitHub Action workflow configuration files were introduced to run all of Core’s automated testing with the intent to fully transition after some time was allowed for testing.

After two full months of testing, the time to finish this transition has come.

We thank TravisCI for testing the codebase through nearly 20 major and many more minor releases.

Merges [49876] to the 4.3 branch.
See #52161. See #50401.

git-svn-id: https://develop.svn.wordpress.org/branches/4.3@49890 602fd350-edb4-49c9-b593-d223f7449a82

.travis.yml

@@ -1,88 +0,0 @@
-sudo: false
-dist: trusty
-language: php
-cache:
-  directories:
-    - $HOME/.npm
-    - vendor
-    - $HOME/.composer/cache
-matrix:
-  include:
-  - php: 5.5
-    env: WP_TRAVISCI=travis:js
-  - php: 5.6
-    env: WP_TRAVISCI=travis:phpunit
-  - php: 5.2
-    env: WP_TRAVISCI=travis:phpunit
-    dist: precise
-  fast_finish: true
-before_install:
-- WP_CORE_DIR=/tmp/wordpress/
-- |
-  if [[ "$WP_TRAVISCI" == "travis:phpunit" ]]; then
-      mysql -e "CREATE DATABASE wordpress_tests;" -uroot
-      cp wp-tests-config-sample.php wp-tests-config.php
-      sed -i "s/youremptytestdbnamehere/wordpress_tests/" wp-tests-config.php
-      sed -i "s/yourusernamehere/travis/" wp-tests-config.php
-      sed -i "s/yourpasswordhere//" wp-tests-config.php
-      svn checkout https://plugins.svn.wordpress.org/wordpress-importer/trunk tests/phpunit/data/plugins/wordpress-importer
-  fi
-before_script:
-- |
-  # Remove Xdebug for a huge performance increase, but not from nightly:
-  stable='^[0-9\.]+$'
-  if [[ "$TRAVIS_PHP_VERSION" =~ $stable ]]; then
-    phpenv config-rm xdebug.ini
-  fi
-- |
-  # Export Composer's global bin dir to PATH, but not on PHP 5.2:
-  if [[ ${TRAVIS_PHP_VERSION:0:3} != "5.2" ]]; then
-    composer config --list --global
-    export PATH=`composer config --list --global | grep '\[home\]' | { read a; echo "${a#* }/vendor/bin:$PATH"; }`
-  fi
-- |
-  # Install the specified version of PHPUnit depending on the PHP version:
-  if [[ "$WP_TRAVISCI" == "travis:phpunit" ]]; then
-    case "$TRAVIS_PHP_VERSION" in
-      7.1|7.0|nightly)
-        echo "Using PHPUnit 5.x"
-        composer global require "phpunit/phpunit:^5"
-        ;;
-      5.6|5.5|5.4|5.3)
-        echo "Using PHPUnit 4.x"
-        composer global require "phpunit/phpunit:^4"
-        ;;
-      5.2)
-        # Do nothing, use default PHPUnit 3.6.x
-        echo "Using default PHPUnit, hopefully 3.6"
-        ;;
-      *)
-        echo "No PHPUnit version handling for PHP version $TRAVIS_PHP_VERSION"
-        exit 1
-        ;;
-    esac
-  fi
-- npm --version
-- node --version
-- nvm install 4.7.2
-- npm install -g grunt-cli
-- npm install
-- npm prune
-- php --version
-- php -m
-- npm --version
-- node --version
-- which phpunit
-- phpunit --version
-- curl --version
-- grunt --version
-- git --version
-- svn --version
-script: grunt $WP_TRAVISCI
-notifications:
-  slack:
-    rooms:
-      secure: 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
-    on_start: never
-    on_failure: always
-    on_success: change