Task: replace master with primary in examples

[deepthi]

local example and region_sharding example have been fixed.
In addition, the following examples need to be cleaned up. Part of the task is to actually run the examples and ensure they aren't broken by the changes.

• compose
• are-you-alive
• operator (this might need to be done in 2 phases, some of it will depend on Inclusive naming planetscale/vitess-operator#214)