Excessive metastore invocations when querying Iceberg table

[findepi]

There was a concern about second call to getTable here #8151 (comment) because these can be expensive.

as

trino/plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/TestIcebergMetastoreAccessOperations.java

Lines 106 to 108 in 30f2ecc

	assertMetastoreInvocations("SELECT * FROM test_select_from",
	ImmutableMultiset.builder()
	.addCopies(GET_TABLE, 12)

shows, we currently do 12 such calls per table when querying Iceberg.

We need to understand why we're doing those additional accesses to metastore.
If caching is found to be desired, #8659 is a WIP adding it.

[findepi]

Out of these 12:

• 4x io.trino.plugin.iceberg.IcebergMetadata#getSystemTable
• 1x io.trino.plugin.iceberg.IcebergMetadata#getMaterializedView
• 1x io.trino.plugin.iceberg.IcebergMetadata#getView
• 2x IcebergMetadata.getTableHandle (apparently within one call)
• 4x IcebergMetadata.getTableMetadata (these seem plain redundant)

cc @homar @joshthoward @clemensvonschwerin

[findepi]

• 4x IcebergMetadata.getTableMetadata (these seem plain redundant)

#8676

[electrum]

Nice analysis. It looks like we will need to change the connector, since it seems hard to avoid all of these.

[findepi]

• 4x io.trino.plugin.iceberg.IcebergMetadata#getSystemTable

#8689

[findepi]

When selecting from a system table, we currently do even more accesses:

    // select from $history
    assertMetastoreInvocations("SELECT * FROM \"test_select_snapshots$history\"",
            ImmutableMultiset.builder()
                    .addCopies(GET_TABLE, 17)
                    .build());

    // select from $snapshots
    assertMetastoreInvocations("SELECT * FROM \"test_select_snapshots$snapshots\"",
            ImmutableMultiset.builder()
                    .addCopies(GET_TABLE, 19)
                    .build());

    // select from $manifests
    assertMetastoreInvocations("SELECT * FROM \"test_select_snapshots$manifests\"",
            ImmutableMultiset.builder()
                    .addCopies(GET_TABLE, 21)
                    .build());

    // select from $partitions
    assertMetastoreInvocations("SELECT * FROM \"test_select_snapshots$partitions\"",
            ImmutableMultiset.builder()
                    .addCopies(GET_TABLE, 17)
                    .build());

    // select from $files
    assertMetastoreInvocations("SELECT * FROM \"test_select_snapshots$files\"",
            ImmutableMultiset.builder()
                    .addCopies(GET_TABLE, 24)
                    .build());

[findepi]

When selecting from a system table, we currently do even more accesses

#8692