remove c rand from the standard retry strategy

[sbiscigl]

Description of changes:

Removes the usage of the c api "rand" from the standard retry strategy in favor of the c++ API random generator std::mt19937. We refactor the thread local instance of std::mt19937 used for pseudo random UUIDs to be used in both UUID and standard retry strategy.

More importantly we remove the usage of srand in the retry strategy constructor that lead to re-initialization of global state for rand each time the constructor was called.

no tests were added as current coverage is sufficient enough

• TestPseudoRandomUUID checks for 1000 UUIDs being generally unique.
• TestStandardRetryStrategy tests the standard retry strategy behavior.

Check all that applies:

• Did a review by yourself.
• Added proper tests to cover this PR. (If tests are not applicable, explain.)
• Checked if this PR is a breaking (APIs have been changed) change.
• Checked if this PR will not introduce cross-platform inconsistent behavior.
• Checked if this PR would require a ReadMe/Wiki update.

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