Refactor Spring Cloud Azure retry options

[saragluna]

As title. To address comments on retry properties: #26970.

amqp.retry:
    max-retries:
    base-delay:
    max-delay:
    try-timeout:
    mode: 'exponential' (default) or 'fixed'
http.retry: 
    mode: 'exponential' (default) or 'fixed'
    exponential:
      max-retries: 
      base-delay:
      max-delay: 
    fixed:
      max-retries: 
      delay:

We also propose to not configure

    retry-after-header
    retry-after-time-unit

This configuration is no longer needed and used to be required by some services (not for users to configure)

Now the configuration properties for HTTP clients will be:

spring.cloud.azure.xxx.retry:
  max-retries: 2
  base-delay: 10s
  max-delay: 2m
  mode: fixed

and AMQP clients will be:

spring.cloud.azure.xxx.retry:
  max-retries: 2
  base-delay: 10s
  max-delay: 2m
  mode: fixed
  try-timeout: 5s