Support Oracle connections without wallet

[Tener]

Overview

The change is backwards compatible. Depends on https://github.com/gravitational/teleport.e/pull/5623 on the db agent side.

The functional changes:

• Oracle proxy will accept both TLS and non-TLS connections and discriminate between the two based on the first byte sent.
• If every db agent for given database instance is at least 17.2.0 (where https://github.com/gravitational/teleport.e/pull/5623 is planned to land), then tsh will show connection instructions that don't depend on Oracle wallet.
• Otherwise, if there are any pre-17.2.0 agents in the mix, the wallet-based instructions will be in effect, but with a message suggesting an upgrade
• Alternative connection strings and other details are printed in debug logs
• Teleport Connect ad is dropped; the Oracle support has known problems there, which should be addressed first.

UX

All new agents:

Started authenticated tunnel for the Oracle database "oracle-dlagon" in cluster "boson.tener.io" on 127.0.0.1:11555.

Use the following command to connect to the Oracle database server using CLI:
  $ sql -L /@localhost:11555/XE

Other clients can use:
  - a direct connection to 127.0.0.1:11555 without a username and password
  - a custom JDBC connection string: 'jdbc:oracle:thin:@tcps://localhost:11555/XE?TNS_ADMIN=/Users/tener/.tsh/keys/boson.tener.io/tener-db/boson.tener.io/oracle-dlagon-wallet'

Some or all old agents:

Started authenticated tunnel for the Oracle database "oracle-dlagon" in cluster "boson.tener.io" on 127.0.0.1:11555.

Use the following command to connect to the Oracle database server using CLI:
  $ sql -L 'jdbc:oracle:thin:@tcps://localhost:11555/XE?TNS_ADMIN=/Users/tener/.tsh/keys/boson.tener.io/tener-db/boson.tener.io/oracle-dlagon-wallet'

You can also connect using Oracle JDBC connection string:
  'jdbc:oracle:thin:@tcps://localhost:11555/XE?TNS_ADMIN=/Users/tener/.tsh/keys/boson.tener.io/tener-db/boson.tener.io/oracle-dlagon-wallet'

Note: for improved client compatibility, upgrade your Teleport cluster. For details rerun this command with --debug.

The --debug messages will show agent counts and alternative connection strings:

2024-12-10T13:40:11+01:00 DEBU [TSH]       Agents for database "oracle-dlagon" with Oracle support: total 2, old 1, new 1. common/proxy.go:392
2024-12-10T13:40:11+01:00 WARN [TSH]       Detected database agents older than 17.2.0. For improved client support upgrade all database agents in your cluster to a newer version. common/proxy.go:395
2024-12-10T13:40:11+01:00 DEBU [TSH]       Building Oracle commands. dbcmd/dbcmd.go:818
2024-12-10T13:40:11+01:00 DEBU [TSH]       Found servers with TCP support: true. dbcmd/dbcmd.go:819
2024-12-10T13:40:11+01:00 DEBU [TSH]       All servers support TCP: false. dbcmd/dbcmd.go:820
2024-12-10T13:40:11+01:00 DEBU [TSH]       Connection strings: dbcmd/dbcmd.go:822
2024-12-10T13:40:11+01:00 DEBU [TSH]       - JDBC: 'jdbc:oracle:thin:@tcps://localhost:11555/XE?TNS_ADMIN=/Users/tener/.tsh/keys/boson.tener.io/tener-db/boson.tener.io/oracle-dlagon-wallet' dbcmd/dbcmd.go:823
2024-12-10T13:40:11+01:00 DEBU [TSH]       - TNS descriptor: /@(DESCRIPTION=(SDU=8000)(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=11555)))(CONNECT_DATA=(SERVICE_NAME=XE))) dbcmd/dbcmd.go:825
2024-12-10T13:40:11+01:00 DEBU [TSH]       - Direct: /@localhost:11555/XE dbcmd/dbcmd.go:826
Started authenticated tunnel for the Oracle database "oracle-dlagon" in cluster "boson.tener.io" on 127.0.0.1:11555.

changelog: Support wider range of Oracle clients and simplified configuration.

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[Tener]

Turns out some clients are surprisingly difficult to configure without the JDBC connection string. I've updated the PR to always show that as an option, even when all agents are new enough to support TCP-only mode.

[GavinFrazar]

LGTM

I tested these combos manually with oracle db [Agent v16.4.0, v17.0.2, v17.0.0-dev] x [tsh v16.4.0, v17.0.0-dev]
where the dev builds were made with this PR + the e update.

All combos worked 👍

[Tener]

Thanks for approvals folks!

Adding 'do-not-merge' for now, we need to time this PR well to ensure the version checks do the right thing.