Refactor FK exception tests

Removed deprecation leftovers

1. `SqliteSchemaManager#_getPortableTableColumnList()` was mistakenly marked `@deprecated` instead of `#_getPortableTableIndexDefinition()` in #3565.
2. `OracleSchemaManager#_getPortableDatabaseDefinition()` was mistakenly marked `@deprecated` instead of `#_getPortableFunctionDefinition()` in #3565.
3. The deprecation message in the `OracleSchemaManager#createDatabase()` description is irrelevant as of #3565.

Remove deprecated stuff for 3.0

Support ForeignKeyConstraintViolationException in SQLite

Fix typos in SQLite

fixed unqualified table name of fk constraints when using schemas

Remove superfluous Configuration instance

Document MySQL error codes

A configuration instance is not strictly required by [DriverManager::getConnection](https://github.com/doctrine/dbal/blob/master/lib/Doctrine/DBAL/DriverManager.php#L139).

As an upside, it doesn't add an extra warning for people that use Psalm/PHPmd when starting off from the documentation example. As the Configuration class has an `@internal` block those tools threat it as the other meaning for `@internal`, as in class that is [internal to the library and not for public use](https://docs.phpdoc.org/references/phpdoc/tags/internal.html).

Fix breaks named parameters in Oracle

Switching Travis CI builds to Ubuntu Bionic Beaver

According to the [documentation](https://docs.travis-ci.com/user/reference/trusty/#container-based-infrastructure), `sudo: false` is no longed needed since Trusty.

Test against PHP 7.4 on AppVeyor

Switching Travis CI builds to Ubuntu Xenial Xerus

Test primarily against PHP 7.4 on Travis

Fix unquoted stmt fragments backslash escaping

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

Use PHP 7.4 instead of a snapshot on Travis

[GH-3777] Don't remove composer lock travis on stable 2.10 branch

Develop branch is gone

Dropped SQL Server 2008 support