`data-id` values must not be typecasted using UI persistence

[mkrecek234]

The newly added decimalSupport in #1981 will not correctly interprete dots and commas.

Steps to reproduce:

• You have a uiPersisdence with decimalSeparator set to comma, and thousandSeparator set to dot (as standard e.g., in Europe).
• You have a form with a model field with type float.
• You enter a value 1.2 into the field (which is incorrect, as dot can only be a thousand separator, so 1.200)

Expected behaviour:

• The entered number is incorrect: If the user wants a decimal value of 1,2 he needs to enter it accordingly. If he wants to enter 1200, he may have entered 1.200
• This should throw a ValidationException as this is an incorrect entry.

Current behaviour:

• The number will be stored as if the user had inputted 1,2 - so the dot - even though as it is a thousandSeparator in that language - will be interpreted as a decimalSeparator...

[mvorisek]

this issue needs a Behat test

the current problem is undetected because of #1985 as the (UI formatted) value is parsed by PHP (on AJAX, what you describe as 1.2 -> 1 issue) but it is silently accepted