SpringBoot Allow Jedis to be selected when both Jedis and Lettuce are on the classpath

Adds ability to choose Redis client when both Lettuce and Jedis on classpath.

Fixes gh-22559

Comment From: snicoll

Thanks @bono007. I've polished things up in https://github.com/spring-projects/spring-boot/commit/589669d0cc49f05381cdf947e69804aa4d720a0d. In particular, I've removed the default value for clientType as it didn't match the code (the real default is that we configure the client based on the classpath).

Comment From: onobc

@snicoll good catch on the default. Thx.