Update size each time to ensure correct data copy in If node

[mangguo321]

Details:

• PortMapHelper initializes the size to 0 during construction and refresh it only inside redefineTo at execution time. However, when the runtime shape is static, redefineTo may be skipped, leaving the size at 0 and causing cpu_convert to use an incorrect element count.
• This PR updates the size from srcMemPtr shape on every redefineTo call, ensure that cpu_convert always receives the correct size

Tickets:

• CVS-183109

[Copilot]

Pull request overview

Fixes an element-count bookkeeping issue in the Intel CPU plugin If node port mapping, ensuring cpu_convert copies/converts the correct number of elements even when the shape stays static at runtime.

Changes:

• Update If::PortMapHelper::redefineTo() to refresh size on every call (not only when output memory descriptors are redefined).

[Copilot]

[HIGH] This is a behavioral bug fix in the If port mapping/data-copy path, but the PR doesn't add a regression test to ensure the element-count passed to cpu_convert is non-zero/accurate when the source memory descriptor is undefined at PortMapHelper construction and the runtime shape is static (the scenario described in the PR). Please add a targeted CPU functional/unit test that reproduces the prior failure (e.g., static runtime shape + required copy/convert between If external/internal memories) to prevent regressions.

[mangguo321]

Done.