Today we log a "deleting snapshots [...] from repository [...]" message at INFO level [almost the first thing](https://github.com/elastic/elasticsearch/blob/dfaec0dbf0c8a0ba2912381334019725848f1f5a/server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java#L1886-L1888) when we start the deletion. However, the requested snapshots may not exist or they may be wildcards to be matched against actual snapshots. In these cases, the log message is either misleading or insuffiicent. Instead we should log the message after we have successfully added the delete to the cluster state similar to how the [logging works for snapshot creation](https://github.com/elastic/elasticsearch/blob/f77c16b78bab5e9f3ee24974aeba408e254e8c94/server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java#L3804).
server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java
if (RepositoriesMetadata.get(state).repository(repositoryName) == null) {
            throw new RepositoryMissingException(repositoryName);
        }
        validate(repositoryName, snapshotName);
    }
    private static void validate(final String repositoryName, final String snapshotName) {
        if (Strings.hasLength(snapshotName) == false) {
            throw new InvalidSnapshotNameException(repositoryName, snapshotName, "cannot be empty");
        }
        if (snapshotName.contains(" ")) {
            throw new InvalidSnapshotNameException(repositoryName, snapshotName, "must not contain whitespace");
        }
        if (snapshotName.contains(",")) {
            throw new InvalidSnapshotNameException(repositoryName, snapshotName, "must not contain ','");
        }
        if (snapshotName.contains("#")) {
            throw new InvalidSnapshotNameException(repositoryName, snapshotName, "must not contain '#'");
        }
        if (snapshotName.charAt(0) == '_') {
            throw new InvalidSnapshotNameException(repositoryName, snapshotName, "must not start with '_'");
        }
        if (snapshotName.toLowerCase(Locale.ROOT).equals(snapshotName) == false) {
            throw new InvalidSnapshotNameException(repositoryName, snapshotName, "must be lowercase");
        }
        if (Strings.validFileName(snapshotName) == false) {
            throw new InvalidSnapshotNameException(
                repositoryName,
                snapshotName,
                "must not contain the following characters " + Strings.INVALID_FILENAME_CHARS
            );