watermark_buffer_test: Break up contiguous memory allocation to avoid bad alloc exception (#12417)
watermark_buffer_test: Break up contiguous memory allocation to avoid bad alloc exception (#12417)

Running this test in CI on Windows we have seen bad alloc exceptions, to
combat this and reduce memory overhead, break up large string allocation
into smaller segments.

Signed-off-by: William A Rowe Jr <6b594a7cef7896b2a5c8742c6f375a4f1966bff1@vmware.com>
Co-authored-by: Sunjay Bhatia <8e0b7e202dd9796d43bda501fc1c3ad47f18345b@vmware.com>
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