feat: Add UI regex validation

[Aditya-ranjan-16]

Description

Add regex validation in ibm_Catalog.json

Git_issue:https://github.ibm.com/GoldenEye/issues/issues/16144

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Release notes content

Add regex validation in ibm_catalog.json

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[ocofaigh]

@Aditya-ranjan-16 As part of this PR could you also please:

• Update resource group input like so:

  variable "existing_resource_group_name" {
    type        = string
    description = "The name of an existing resource group to provision the resources. [Learn more](https://cloud.ibm.com/docs/account?topic=account-rgs&interface=ui#create_rgs) about how to create a resource group."
    default     = "Default"
  }
  

• Remove the default_value and description from the "existing_resource_group_name" input in the ibm_catalog.json

[Aditya-ranjan-16]

@Aditya-ranjan-16 As part of this PR could you also please:

• Update resource group input like so:

  variable "existing_resource_group_name" {
    type        = string
    description = "The name of an existing resource group to provision the resources. [Learn more](https://cloud.ibm.com/docs/account?topic=account-rgs&interface=ui#create_rgs) about how to create a resource group."
    default     = "Default"
  }
  

• Remove the default_value and description from the "existing_resource_group_name" input in the ibm_catalog.json

done