RFR: 8292269: Log more CDS failure messages in the warning channel [v6]

[Matias Saavedra Silva]

> When -Xshare:auto is used, FileMapInfo::fail_continue() prints the diagnostic message to the Info channel instead of Warning. This was necessary in the past because CDS would failed to load for many reasons (e.g., failure to mmap due to ASLR) that are not the fault of the user. If we printed the message in the Warning channel, the user would be overwhelmed and would ultimately ignore the warnings, rendering them useless.
> 
> However, currently CDS is much more reliable. For some error conditions that require user attention, we should consider changing the failure logs to use the Warning channel.
> 
> Logging will now shift toward Unified Logging, so `fail_continue()` will be replaced with `log_info(cds)` and `log_warning(cds)`. Relevant tests are updated to accommodate this change. Verified with tier1-4 tests

Matias Saavedra Silva has updated the pull request incrementally with one additional commit since the last revision:

  Fixed a merge issue

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12419/files
  - new: https://git.openjdk.org/jdk/pull/12419/files/22f85539..30d488c7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12419&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12419&range=04-05

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12419.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12419/head:pull/12419

PR: https://git.openjdk.org/jdk/pull/12419