Replace ltrim with str_replace in json_form_widget

[janette]

An ltrim followed by a second parameter will trim any matching contiguous character(s) from the left side of the email address. e.g. matildafoo@test.com will become dafoo@test.com

Switching to str_replace will result in only removing an exact match on "mailto:"

QA Steps

• Create a dataset, fill in the ContactPoint email field with "matildafoo@test.com", and save
• view or edit the dataset to confirm the value was saved correctly

[tiffneybare]

Looks good locally