Contact form: short term modifications to reduce superflous ops escalation

From https://code.greenhost.net/greenhost/website/-/issues/545

For now every time a customer check urgent in the contact form, it notify the on-call ops via Pagerduty, which is a bit much. There's a long term plan to be made about how the form should contact ops in https://code.greenhost.net/greenhost/greenhost/-/issues/596 , but before we discuss and implement all this, lets' change what can be easily changed to make it clear to customer that this toggle should only be used in case of emergencies.

Propositions done during last hosting meeting:

• Change the text to type from "URGENT" to "I agree"
• Make it clear that depending on the type of issue we might not take action immediately
• Put a value on the hourly rate
• Change the term from "urgent" to "emergency"