fix(rfs-size-range): Update size validation range for regional file shares

[deepakibms]

make test-vpc TEST_NAME=TestAccIbmIsShareRegionalShare 
Running VPC test: TestAccIbmIsShareRegionalShare
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./ibm/service/vpc -v -run=TestAccIbmIsShareRegionalShare -timeout 700m
=== RUN   TestAccIbmIsShareRegionalShare
--- PASS: TestAccIbmIsShareRegionalShare (90.13s)
PASS
ok      github.com/IBM-Cloud/terraform-provider-ibm/ibm/service/vpc     92.567s



make test-vpc TEST_NAME=TestAccIbmIsShareBasic         
Running VPC test: TestAccIbmIsShareBasic
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./ibm/service/vpc -v -run=TestAccIbmIsShareBasic -timeout 700m 
=== RUN   TestAccIbmIsShareBasic
--- PASS: TestAccIbmIsShareBasic (60.30s)
PASS
ok      github.com/IBM-Cloud/terraform-provider-ibm/ibm/service/vpc     62.237s

[uibm]

lgtm