RFR: 8350916: Remove misleading warning "Cannot dump shared archive while using shared archive" [v2]

[Ioi Lam]

> Please review this trivial change. I replaced an unreachable `warning()` call with an assert and an explanation in comments.
> 
> I verified with running all CDS tests and the assert is never triggered.

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  @calvinccheung comment - fixed typo

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/23836/files
  - new: https://git.openjdk.org/jdk/pull/23836/files/207efa30..414756e7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23836&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23836&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23836.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23836/head:pull/23836

PR: https://git.openjdk.org/jdk/pull/23836